TRVS XV The Fifthteenth International Conference

on Time-Resolved Vibrational

Spectroscopy

June 19.-24. 2011

Centro Stefano Franscini, Monte Verità, Ascona,

Switzerland

The conference is supported in part by generous donations from the following

companies:

Gold Sponsor

Local Organizer

Peter Hamm, University of Zurich, Switzerland

International Organizing Committee:

George H. Atkinson, University of Arizona, USA Huib Bakker, FOM Institute for Atomic and Molecular Physics (AMOLF), The

Netherlands Salvatore Califano, LENS, University of Florence, Italy Paul M. Champion, Northeastern University, USA Thomas Elsaesser, Max-Born-Institute, Berlin, Germany Marloes Groot, Vrije Universiteit, Amsterdam, The Netherlands Terry L. Gustafson, Ohio State University, Columbus, USA Peter Hamm, Universität Zürich, Switzerland Edwin J. Heilweil, National Institute of STDS & Technology (NIST), Gaithersburg, USA Robin Hochstrasser, University of Pennsylvania, Philadelphia, USA Alfred Laubereau, Technical University of Munich, Germany Stephen Meech, University of East Anglia, UK Yasuhisa Mizutani, Osaka University, Japan Shaul Mukamel, University of California-Irvine, USA Keith Nelson, Massachusetts Institute of Technology, USA Erik Nibbering, Max Born Institute, Germany Jennifer Ogilvie, University of Michigan, USA Roberto Righini, LENS, University of Florence, Italy Cather Simpson, University of Auckland, New Zealand Tahei Tahara, RIKEN, Japan Andrei Tokmakoff, Massachusetts Institute of Technology, USA Kei Tominaga, Kobe University, Japan Hajime Torii, Shizuoka University, Japan Klaas Wynne, University of Glasgow, UK Martin Zanni, University of Wisconsin, Madison, USA Larry Ziegler, Boston University,USA Wolfgang Zinth, University of Munich, Germany

Conference Program

SUNDAY MONDAY TUESDAY WEDNESDAY THURSDAY FRIDAY

Coffee

Welcome Hochstrasser Elsaesser Woutersen Massari Bonn Tahara

Mukamel Torii Jones Hauer Geva Hynes Pshenichnikov

McCamant Nibbering Ogilvie Kubarych Umapathy Bakker Tominaga

Zinth Wachtveitl van Thor Mizutani Kennis Heilweil Groot

Wynne Meech Vos Righini Meuwly Buckup Lang

Lunch Coffee

Arrival Asbury Lian Lu Borguet Vöhringer Wolf Raschke

Dyer Kandori Barth Hauser Vaziri Gerwert Heberle

Excursion Zanni Gaffney Hunt Cheatum Gustafson Crim Nelson

Departure

Welcome Dinner

Dinner Dinner Conference Dinner

Free Evening

Poster Session Poster Session

Monday 8.30 - 8.40 Welcome

8.40 - 9.20 Robin Hochstrasser: Vibrational Probes of Associated Water Dynamics

9.20 - 9.50 Thomas Elsaesser: Vibrational motions, charge relocations and chemical processes mapped by femtosecond x-ray diffraction

9.50 - 10.10 Sander Woutersen: Slippery when wet: lubricating a molecular machine with water

10.10-10.40 Coffee Break

10.40-10.50 A brief history of Monte Verita

10.50-11.20 Aaron Massari: Nonlinear Spectroscopic Investigations of Organic Semiconductors

11.20-11.40 Mischa Bonn: Ultrafast 2-dimensional surface vibrational spectroscopy of water interfaces

11.40-12.00 Tahai Tahara: Heterodyne-Detected Vibrational Sum-Frequency Generation and Its Extension to Time-Resolved Measurements

12.00-14.30 Lunch

14.30-15.00 John Asbury: Ultrafast solvatochromism assisted vibrational spectroscopy of solar energy materials

15.00-15.30 Tim Lian: Probing interfacial electron transfer dynamics in photovoltaic and photocatalytic nanomaterials by time-resolved vibration spectroscopy

15.30-15.50 Peter Lu: AFM-Raman Imaging Analysis of Single-Molecule Interfacial Electron Transfer Dynamics and Single-Electron Self-Exchange Fluctuations

15.50-16.10 Eric Borguet: Interfacial depth profiling and the effect of electric fields at a charged solid-aqueous interface on the ultrafast vibrational relaxation of water

16.10-16.40 Coffee Break

16.40-17.00 Peter Vöhringer: Fs-2DIR-probing of the internal dynamics of supramolecular complexes

17.00-17.30 Martin Wolf: Vibrational and electronic dynamics in correlated solid state materials probed by time-resoled photoemission spectroscopy

17.30-18.00 Markus Raschke: Ultrafast vibrational near-field spectroscopy

Tuesday

8.30 - 9.10 Shaul Mukamel: New directions in multidimensional optical spectroscopy

9.10 - 9.30 Hajime Torii: Intermolecular Electron Density Modulations in Water Related to Vibrational Couplings and Intensities: OH Stretching and Terahertz

9.30 - 9.50 Kevin Jones: Trpzip2 Kinetics Revealed Through Isotope-Edited Transient Temperature-Jump 2D IR Spectroscopy

9.50 - 10.10 Jürgen Hauer: Visualizing Wavepacket Dynamics through a Conical Intersection by Two-Dimensional Electronic Spectroscopy

10.10-10.40 Coffee Break

10.40-11.10 Eitan Geva: Nonequilibrium relaxation dynamics of vibrationally excited molecules in liquid solution and its effect on their multidimensional infrared spectra

11.10-11.40 Casey Hynes: Water reorientation around amphiphiles and 2D infrared spectroscopy

11.40-12.00 Maxim Pshenichnikov: 2D IR Spectroscopy of Water Dynamics near Hydrophobes

12.00-14.30 Lunch

14.30-15.00 Brian Dyer: Residue specific resolution of protein folding dynamics using time-resolved infrared spectroscopy

15.00-15.30 Hideki Kandori: Role of Protein-Bound Water Molecules in Rhodopsins

15.30-15.50 Andreas Barth: Structures of the early oligomers in the aggregation of the Alzheimer’s peptide

15.50-16.10 Karin Hauser: Peptide folding dynamics studied by temperature-jump infrared-spectroscopy combined with different isotopic substitution methods

16.10-16.50 Coffee Break

16.40-17.00 Alipasha Vaziri: Mechanisms of ion-transport and selectivity in ion-channels

17.00-17.30 Klaus Gerwert: Protein-Interactions: spatio-temporal resolved at atomic detail.

17.30-18.00 Joachim Heberle: Surface-enhanced IR spectroscopy of solid-supported membrane proteins

Wednesday

8.30 - 9.00 David McCamant: Time-resolved and two-dimensional femtosecond stimulated Raman spectroscopy

9.00 - 9.20 Erik Nibbering: Transient Response of the OH Stretching Mode of Photoacids

9.20 - 9.40 Jeniffer Ogilvie: Development of Two-dimensional Electronic Femtosecond Stimulated Raman Spectroscopy (2DE-FSRS) and its First Applications

9.40 - 10.00 Kevin Kubarych: Dynamics at the Protein-Water Interface Revealed by 2DIR Spectroscopy

10.00-10.40 Coffee Break

10.40-11.10 Siva Umapathy: Ultrafast Raman loss spectroscopic (URLS) study of excited state evolution of -terthiophene

11.10-11.40 Huib Bakker: Femtosecond vibrational study of water dynamics in salt solutions

11.40-12.00 Keisuke Tominaga: Comparison of Frequency Fluctuation between the Vibrational State and Electronic State in Aqueous Solution

12.00 Lunch and Excursion

Thursday

8.30 - 9.00 Wolfgang Zinth: Formation of DNA photolesions resolved by transient IR-spectroscopy

9.00 - 9.30 Joseph Wachtveitl: The photo-induced decarboxylation of nitrophenylacetates

9.30 - 9.50 Jasper van Thor: Ultrafast vibrational dynamics of parallel excited state proton transfer reactions in the Green Fluorescent Protein

9.50 - 10.10 Yasuhisa Mizutani: Watching energy flow in hemeproteins

10.10-10.40 Coffee Break

10.40-11.10 John Kennis: Ultrafast Infrared and Stimulated Raman Spectroscopy of Biomolecules

11.10-11.30 Ted Heilweil: Engineering femtosecond chemistry for the development of efficient organometallic photochromes

11.30-11.50 Marloes Groot: Conversion of light into chemical energy: Electron transfer processes in Photosystem I and the bacterial reaction center-light harvesting 1 complex

12.00-14.30 Lunch

14.30-15.00 Martin Zanni: Selecting the structural resolution: 2D IR spectroscopy and native chemical ligation

15.00-15.30 Kelly Gaffney: H-bond switching and ligand exchange dynamics in aqueous ionic solution

15.30-15.50 Neil Hunt: The Role of CN and CO Ligands in the Vibrational Relaxation Dynamics of Model Compounds of the [FeFe]-Hydrogenase Enzyme

15.50-16.10 Christopher M. Cheatum: The Dynamic Signature of the Enzymatic Transition State Probed by 2D IR Spectroscopy

16.10-16.50 Coffee Break

16.40-17.00 Terry Gustafson: Electron Delocalization in the Singlet and Triplet States of MM (M = Mo or W) Quadruply Bonded Complexes Supported By Carboxylate and Amidinate Ligands

17.00-17.30 Fleming Crim: Time-resolved studies of isomerization and vibrational relaxation in liquids and cryogenic matrices

17.30-18.00 Keith Nelson: Nonlinear THz spectroscopy and coherent THz control

Friday

8.30 - 9.00 Klaas Wynne: Terahertz dynamics of water in eutectic LiCl solution: bulk water and worm-hole structures

9.00 - 9.30 Steve Meech: H-bond structures and structural relaxation in aqueous solutions of electrolytes

9.30 - 9.50 Marten Vos: Ultrafast dynamics of photolyzed carbon monoxide in the primary docking site of heme domain variants of the oxygen sensor FixL

9.50 - 10.10 Roberto Righini: Tetracycline structure and dynamics in methyl sulfoxide

10.10-10.40 Coffee Break

10.40-11.10 Markus Meuwly: Learning about Intermolecular Interactions from Spectroscopic Probes in Proteins and Solution

11.10-11.30 Tiago Buckup: Ground- and Excited State Vibrational Coherence Dynamics in all-trans Retinal Protonated Schiff-Bases investigated with (Pump) DFWM

11.30-11.50 Bernhard Lang: Tracking the Pathway of an Ultrafast Photoinduced Bimolecular Charge Separation Reaction

12.00-14.30 Lunch and Departure

Poster Sessions Posters will be up for the whole conference. Poster Sessions are Monday, 20.00-22.00 and Tuesday 20.00-22.00. Posters with even numbers should be presented on Monday, those with odd numbers on Tuesday. Poster format is A0, portrait format.

1. Katrin Adamczyk: The Role of Protein–Ligand Interactions in Ligand Binding and Equilibrium Structural Fluctuations of Myoglobin

2. Satoshi Ashihara: Temperature dependence of vibrational relaxation of the OH bending excitation in liquid H2O

3. Ellen H. G. Backus: Ultrafast vibrational probing of heat transport through model membrane systems

4. Tiago Buckup: Selective Response Preparation and Interference Phenomena in ultrafast spectrally resolved Degenerate Four-Wave-Mixing

5. Marco Candalaresi: Investigation of the Dynamics of Nitrosylated Corynebacterium glutamicum Catalase Protein by Fourier transform-2D-IR Spectroscopy

6. S.V. Chekalin: Ultrafast vibrational dynamics in free polyatomic molecules excited by IR femtosecond radiation

7. Wutharath Chin: Vibrational relaxation of small molecules isolated in low-temperature matrices.

8. Niklas Christensson: Vibrational Dynamics of [Lu(Pc)2]-1 Probed with Broadband

Pump-Probe and Two-dimensional Electronic Spectroscopy

9. Chris Colley: Characterization of Laser Emission at High Spectral Resolution on a Nanosecond Timescale

10. Andreas A. Deeg: Light-triggered aggregation and disassembly dynamics of amyloid-like structures from picoseconds to minutes.

11. Arend G. Dijkstra: Modeling amide I and II modes in polypeptides

12. Mariangela Di Donato: Time resolved infrared study of the recombination dynamics of the carbon monoxide complex of Bacillus subtilis truncated hemoglobin.

13. Paul Donaldson: UV/Visible pump, Infrared probe experiments for challenging samples: transient gratings and heterodyne detection

14. Julien Rehault: Amplification of Linear Dichroism for Ultrasensitive Femtosecond IR Spectroscopy

15. Mateusz Donten: Laser induced pH jumps: oNBA proton release and pH equilibration

16. Kelly A Fransted: Probing impulsive vibrational dynamics near conical intersections

17. Ziad Ganim: Signatures of Ion Transport Intermediates in the KcsA Potassium Channel

18. Sean Garrett-Roe: Heterogeneous dynamics of liquid water by ultrafast vibrational spectroscopy (3D-IR) and complex network analysis

19. Terry L. Gustafson: Excited State Vibrational Analysis of N,N’-Dioctyl Perylene Diimide and its Anion

20. Ted Heilweil: Time-resolved vibrational spectroscopy of [FeFe]-hydrogenase active site model compounds

21. Jan Helbing: A compact implementation of Fourier transform 2D-IR and transient 2D-IR spectroscopy without phase ambiguity

22. Karsten Heyne: Optimization of the Pr phytochrome photoisomerization by pre-twisting of the chromophore ground state: A polarization resolved fs VIS pump – IR probe study

23. Cho-Shuen Hsieh: Ultrafast Reorientation of Dangling O-H Groups at the Air/Water Interface

24. Adrian Huerta Viga: Salt Bridge Interactions in Solution Probed Using Two-Dimensional Vibrational Spectroscopy

25. Johannes Hunger: Effect of Protons and Hydroxide Ions on the Dynamics of Water

26. Søren Rud Keiding: Vibrational Relaxation in Aqueous Formamide

27. John T. King: Dynamics near the Glass Transition: Using 2DIR to Study Dynamic Heterogeneity

28. Gregor Knopp: Investigation of low frequency vibrations by time-frequency analysis of dispersed fs –FWM

29. Jörg Kohl-Landgraf: Spiropyrans in aqueous media

30. Philip Kraack: Dependence of Vibrational Coherence Dynamics in all-trans retinal in Bacteriorhodopsin on excitation wavelengths

31. Hikaru Kuramochi: Ultrafast Excited-State Structural Dynamics in Photoactive Yellow Protein Chromophore Revealed by Tunable UV-Femtosecond Stimulated Raman Spectroscopy

32. Jennifer E. Laaser: Shaping SFG: advantages of mid-IR pulse shaping for heterodyned and time-domain data collection

33. Andrea Lapini: Transient Infrared Spectroscopy: A new approach to investigate Valence Tautomeric Interconversion

34. Joshua Lessing: Finding order in disordered peptides: A 2D IR study of the structure and dynamics in elastin-like peptides

35. Chungwen Liang: Proton Transport in Biological Systems can be Probed by Two-dimensional Infrared Spectroscopy

36. Casey H. Londergan: Novel Natural and Artificial Side Chains Sensitive to Protein Hydration Detected by Infrared and Raman Spectroscopy

37. Andras Lukacs: Direct Evidence that Flavin Photoexcitation Modulates the Chromophore Environment in AppA on the Ultrafast Timescale

38. Alexander L. Malinovsky: Time-Resolved Raman Spectroscopy of Intramolecular Vibrational Redistribution in Terminal Acetylene Molecules.

39. Marie S. Marek: Dependence of the ultrafast initial dynamics of carotenoids on the conjugation length (N) studied by multidimensional spectroscopy

40. Kamila Mazur: Hydration water dynamics at biological interfaces: peptides and proteins studies

41. Henrike Müller-Werkmeister: Artificial amino acids as versatile tools for 2D-IR studies of proteins

42. Ryosuko Nakamura: Stimulated Raman Spectroscopy of the Electronic Excited State of Photoactive Yellow Protein

43. Michel Negrerie: Picosecond Iron Motion Triggered by Nitric Oxide Binding to Hemoglobin

44. Masanari Okuno: Time-resolved CARS spectral imaging using a nanosecond white-light laser source

45. Matthijs R. Panman: Divide and conquer – distinguishing between fluxionality and vibrational energy transfer in Fe(CO)4(olefin) complexes.

46. Vlad G. Pavelyev: Aggregation of Amphiphilic Molecules in Aqueous Solutions

47. Brandt Pein: Ultrafast 3D IR-Raman pump-probe spectroscopy to monitor spatially-resolved energy transfer in nitrobenzene

48. Chunte Sam Peng: 2D IR Spectroscopy of Nucleic Acid Bases

49. Fivos Perakis: Two Dimensional Infrared Spectroscopy of Ice Ih

50. Lukasz Piatkowski: Ultrafast vibrational energy relaxation of the water bridge

51. Emanuele Pontecorvo: Snapshots of ligand-hemeprotein interaction taken with sub-picosecond time resolution

52. Ruben Pool: Phase-sensitive sum-frequency generation spectroscopy achieved by heterodyne detection at aqueous interfaces

53. Alexander Rodenberg: Photocatalytic Generation of Hydrogen in Water as Solvent Spectroscopic Insights into the Mechanism

54. Santanu Roy: Solvent and Conformation Dependence of Amide I Vibrations in Proteins with Proline

55. William Rock: Ground State Proton Transfer Rate Measurement by 2D IR Spectroscopy

56. Almis Serbenta: Ultrafast hole transfer dynamics in polymer:fullerene blends

57. Keisuke Tominaga: Vibrational Dynamics of [RuCl5(NO)]2- in Aqueous Solution Studied by Nonlinear Infrared Spectroscopy

58. Keisuke Tominaga: Frequency Dependence of Vibrational Energy Relaxation and Spectral Diffusion of Pyrrole-base Complexes in Solution

59. David R. Skoff: Structural determination of the protein human -synuclein associated with a lipid bilayer using two-dimensional IR spectroscopy

60. Tibert H. van der Loop: Spheres and tubes: the influence of geometry on the structure and dynamics of nano-confined water

61. Sietse T. van der Post: The Effect of Cations on the Anionic Hydration Shell

62. Luuk van Wilderen: Rearrangements of hydrogen-bonding interactions in the solvation shell of a photoswitchable catalyst

63. Peter Vöhringer: Vibrational dynamics in hydrogen-bonded chains

64. Amir Wand: Ultrafast Investigation of Excited State Dynamics of the Photochromic Anabaena Sensory Rhodopsin

65. Zhengrong Wei: Tracking the Ultrafast Wavepacket Motion in Barrierless Cyanine Photoisomerization by Femtosecond Pump-Dump-Probe Spectroscopy

66. Klaas Wynne: Terahertz dynamics and structure of protic ionic liquids

67. Ming Yang: Ultrafast Two-Dimensional Infrared Spectroscopy of DNA Oligomers at Different Hydration Levels

68. Ming Yang: Ultrafast Dynamics and Couplings of N-H Stretching Excitations of Guanosine-Cytidine Base Pairs in Solution

69. Masayuki Yoshizawa: Resonant Stimulated Raman Spectroscopy of the S1 and S* Excited States of Carotenoids in Light-Harvesting Complex

70. Zhen Zhang: Ultrafast 2-Dimensional Surface Vibrational Spectroscopy of Water at Lipid Interfaces

Abstracts Talks Monday

Vibrational Probes of Associated Water Dynamics

Ayanjeet Ghosh1, Daniel Kuroda1 and Robin Hochstrasser1

1 University of Pennsylvania, Philadelphia, PA19104

(Hochstra@sas.upenn.edu)

Water enables biomolecular function through its role in the equilibrium structures and

stability of biomolecules, yet the structural-dynamics of water in association with

macromolecules requires more evidence and theory and experiments are not sharply related.

The structural motions of water confined near proteins are different from those of liquid

water: the protein function might require water molecules in rapid motion, interacting with the

backbone and side chains as well as with one another. The chemical physics of such

elementary interactions is challenging and potentially rewarding. One obvious benefit will be

the discovery of new drugs. This utility is exemplified by the M2 channel of the Influenza A

virus, a main topic of this talk1, for which the drug amantadine was once a significant antiviral

medication that saved many lives. Apparently the drug effectively slowed the influx of

protons by directly blocking the flow of water containing hydronium ions into channel.

However the virus has since mutated its transmembrane region to render this class of drugs

totally ineffective so that infection by Influenza A remains as a serious human health issue.

Thus, there is a medical need to understand the microscopic mechanisms of action of the M2

proton channel and its confined water and help contribute to the design of inhibitors that

target current forms of M2.

Two dimensional infrared experiments that use isotope replacement (13C=18O) on specific

residues are used to characterize the contributions to the mode spectral density of water

molecules confined in the M2 channel as the structures are altered by changes in the ambient

conditions. The properties of the M2 confined water are shown to be different in the presence

and the absence of drugs having known bound structures. To accomplish these results reliable

approaches are needed to employ 2D IR data to determine frequency fluctuation spectra and

the effects of water structural dynamics on the observations. The effectiveness of the slope

method as a means of describing the 2D IR shape is evaluated for amide and other modes.

The frequency relaxations of amide-I modes, amino acid side chains and carboxylate ions will

be discussed in relation to their water structural dynamics.

1. Ghosh, J. Qiu, W.F. DeGrado, R. Hochstrasser, M., Proceedings of the National Academy

of Sciences of the United States of America, (2011) 108 (15) 6115-6120

Vibrational Motions, Charge Relocations and Chemical Processes Mapped

by Femtosecond X-Ray Diffraction

Thomas Elsaesser, Flavio Zamponi, Philip Rothhardt, Michael Woerner

Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Str. 2 a,

12489 Berlin, Germany, elsasser@mbi-berlin.de

Femtosecond x-ray diffraction allows for probing structural dynamics on atomic length and

ultrafast time scales by deriving transient atomic positions and electron density distributions

from diffraction patterns. After femtosecond vibrational or electronic excitation, synchronized

hard x-ray pulses of 100 fs duration are diffracted from the excited sample, a powder of small

crystallites, to map vibrational motions, charge relocations and the formation of new

molecular species in a time-resolved way. In this contribution, we present new results on

ultrafast structure changes in molecular materials forming ionic hydrogen-bonded crystal

structures. A first experiment shows that coherent low-frequency lattice motions steer strong

charge relocations in potassium dihydrogen phosphate [KH2PO4, KDP]. The spatial amplitude

of charge relocation is 30 times larger than the vibrational amplitudes, resulting in a strong

electric polarization. The data reveal the multi-mode character of vibrational motions

including the anharmonically coupled LO and TO (soft mode) phonon cordinates. A second

series of experiments gives evidence of a so far unknown concerted transfer of electrons and

protons in ammonium sulfate [(NH4)2SO4]. Within 100 fs, charge transfer from the SO4

groups generates a highly confined electron channel along the c-axis of the unit cell which is

stabilized by transferring protons from the adjacent NH4 groups into the channel. Time-

dependent charge density maps display a periodic modulation of the channel’s charge density

by low-frequency lattice motions with a concerted electron and proton motion between the

channel and the initial proton binding site.

References:

[1] T. Elsaesser, M. Woerner, Acta Cryst. A 66 (2010) 168.

[2] F. Zamponi, Z. Ansari, M. Woerner, T. Elsaesser, Opt. Express 18 (2010) 947.

[3] M. Woerner, F. Zamponi, Z. Ansari, J. Dreyer, B. Freyer, M. Prémont-Schwarz,

T. Elsaesser, J. Chem. Phys. 133 (2010) 064509.

Slippery when wet: lubricating a molecular machine with water

Matthijs R. Panman1, Bert H. Bakker1, Euan R. Kay2, Wybren Jan Buma1,

Albert M. Brouwer1, David A. Leigh2, and Sander Woutersen1

1Van ’t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904,

1098 XH Amsterdam, The Netherlands; email: s.woutersen@uva.nl

2School of Chemistry, University of Edinburgh, King’s Buildings, West Mains Road,

Edinburgh EH9 3JJ, UK

The presence of water is known to be essential for the functionality of biomolecular

machinery (“the lubricant of life”), but it is as yet not well understood how water facilitates

this functionality. We use time-resolved vibrational spectroscopy to investigate the motion of

much smaller, synthetic molecular machines (see left figure), the motion of which can be

photo-triggered [1]. To our surprise, we have recently discovered that adding small amounts

of water to the solvent (acetonitrile) dramatically speeds up the motion of these molecular

machines: adding a few % doubles the shuttling rate (see right figure). Perhaps even more

surprisingly, adding similar or even larger amounts of MeOH does not speed up the motion,

whereas adding tert-butanol even slows it down. Water molecules apparently act as an

effective ‘lubricating agent’ for hydrogen-bonded molecular machines. Using transient

vibrational spectroscopy of the amide I modes of the shuttling macrocycle and of the initial

and final stations, we investigate the mechanism by which water speeds up the shuttling

motion. Since the moving parts of the molecular shuttle are connected by CO···HN hydrogen

bonds between peptide groups, very similar to the ones giving rise to the two most common

secondary protein structures, these results should have significant biophysical implications.

References:

[1] M.R. Panman et al., Science 328 (2010), 1255.

Nonlinear Spectroscopic Investigations of Organic Semiconductors

Aaron M. Massari1

1 University of Minnesota, Minneapolis, MN, USA, massari@umn.edu

Two-dimensional IR vibrational echo spectroscopy (2D-IR VES) provides information

about structural dynamics that one-dimensional approaches cannot, enabling one to measure

the fast changes in molecular configurations in organic semiconductors that occur on time

scales that are comparable to site-to-site charge hopping events. It has been reported that

these dynamics should play an important role in limiting the carrier conduction through the

bulk (space-charge) of organic thin films.[1] To this end, our group has initiated a series of

experiments that seek to identify the time scales of structural motions that are correlated with

changes in mobility.[2,3] These experiments rely on polymeric thin films whose

conductivities can be manipulated in some way so that we can then measure the resulting

changes in dynamics with each perturbation. In this talk, I will describe our recent

experimental results studying poly(aniline) (PANI) as a model system whose charge

mobilities can be adjusted through chemical and electrochemical treatments. Our initial

efforts have looked at thin films of PANI in their doped and undoped states and we have also

looked at the impact on the structural dynamics of repeated dedoping/redoping cycles. A

particularly intriguing result is that the dynamics that we measure with 2D-IR reflect a

memory of the treatments that were applied to the films, whereas many other steady-state

measurements would suggest that there is no static memory of the film history.

References:

[1] Troisi, A.; Orlandi, G., J. Phys. Chem. A 110 (2006) 4065.

[2] Eigner, A. A.; Anglin, T. C.; Massari, A. M., J. Phys. Chem. C 114, (2010) 12308.

[3] Eigner, A. A.; Jones, B. H.; Koprucki, B. W.; Massari, A. M., J. Phys. Chem. B (2011)

accepted.

SFG Intensity

2800

2700

2600

2500

2400

IR fre

quen

cy(c

m-1

)

2800

2700

2600

2500

2400Det

ect

ion

freq

uenc

y (c

m-1

)

280026002400Excitation frequency (cm

-1)

0 fs

Ultrafast 2-Dimensional Surface Vibrational Spectroscopy of Water

Interfaces

Zhen Zhang1, Lukasz Piatkowski1, Huib J. Bakker1, and Mischa Bonn1

1 zhang@amolf.nl, piatkowski@amolf.nl, bakker@amolf.nl, bonn@amolf.nl,

FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands.

At the surface or interface of water, the water hydrogen-bonded network is abruptly

interrupted, conferring properties on interfacial water different from bulk water. Despite its

importance for disciplines such as electrochemistry, atmospheric chemistry and membrane

biophysics, the structure of interfacial water has remained highly debated. We elucidate the

structure and structural dynamics of interfacial water using ultrafast two-dimensional surface-

specific vibrational spectroscopy [1]. We present data for the water-air and water-lipid

interfaces, which reveal interfaces that are structurally heterogeneous, yet highly dynamical.

We determine the timescale on which the heterogeneity decays and reveal the presence of

surprisingly rapid inter- and intramolecular energy transfer processes.

Fig. 1 Time-resolved 2D-SFG data for interfacial water at the water/air interface at zero delay

time between pump and probe. The right panel shows the static SFG spectrum. The 2D

spectrum reveals an on-diagonal response with a slope smaller than one (dashed line indicates

slope of 1), expected for a heterogeneous surface. Off-diagonal peaks are highlighted by

dotted circles.

References:

[1] J. Bredenbeck, A. Ghosh, H.K. Nienhuys, and M. Bonn, Acc. Chem. Res. 42 (2009) 1332.

Heterodyne-Detected Vibrational Sum-Frequency Generation

and Its Extension to Time-Resolved Measurements

Satoshi Nihonyanagi, Prashant Chandra Singh, Shoichi Yamaguchi, and Tahei Tahara

Molecular Spectroscopy Laboratory, Advanced Science Institute (ASI), RIKEN,

2-1 Hirosawa, Wako 351-0198, Japan

email address: tahei@riken.jp

Vibrational sum-frequency generation (VSFG) provides interface-selective vibrational

spectra and is an indispensable tool to study molecular properties at interfaces. Recently, we

realized multiplex phase-sensitive heterodyne-detection of VSFG (HD-VSFG) which enabled

us to measure the imaginary and real parts of the vibrationally resonant second-order

susceptibility ((2)) [1]. This HD-VSFG has a number of advantages over the traditional

homodyne-detected VSFG which can provide only information about |(2)|2. For example, the

imaginary (2) (Im (2)) spectra at the interface obtained with HD-VSFG can be directly

compared with bulk infrared spectra that corresponds to Im (1), and the sign of Im (2)

includes unambiguous information about the absolute orientation of interfacial molecules.

Using these characteristics of HD-VSFG, we demonstrated flip-flop of the water orientation

at the water interfaces with charged surfactants [1] as well as charged lipids [2], and showed

that there is no “ice-like” water structure at the charged water interface [3]. In this

presentation, we report on the extension of HD-VSFG spectroscopy to time-resolved

measurements. Combining irradiation of a femtosecond infrared pump pulse with HD-VSFG

measurements, we have successfully observed ultrafast dynamics at interfaces through the

temporal change of Im (2) spectra. The obtained time-resolved Im (2) spectra are readily

interpreted as time-resolved infrared spectra in the bulk and provide rich information about

ultrafast dynamics at liquid interfaces.

References:

[1] S. Nihonyanagi, S. Yamaguchi, T. Tahara, J. Chem. Phys., 130 (2009) 204704.

[2] J. A. Mondal, S. Nihonyanagi, S. Yamaguchi, T. Tahara, J. Am. Chem. Soc., 132 (2010) 10656.

[3] S. Nihonyanagi, S. Yamaguchi, T. Tahara, J. Am. Chem. Soc., 132 (2010) 6867.

Ultrafast Solvatochromism Assisted Vibrational Spectroscopy of Solar

Energy Materials

Ryan D. Pensack1 and John B. Asbury1

1 Department of Chemistry, The Pennsylvania State University, University Park, PA USA

Organic solar cells are promising candidates for inexpensive photovoltaics for large area

applications, but their efficiencies are limited by partial overlap with the solar spectrum.

Efforts to extend the absorption spectrum of have revealed that only certain ‘magic’ materials

seem to produce more efficient devices. To elucidate the origin of this behavior, we

undertook a study of the dynamics of charge separation in a photovoltaic polymer blend

consisting of the conjugated polymer, CN-MEH-PPV, blended with the electron accepting

functionalized fullerene, PCBM, using ultrafast Solvatochromism Assisted Vibrational

Spectroscopy (SAVS).[1] We take advantage of a solvatochromic shift of the vibrational

frequency of the carbonyl (C=O) stretch of PCBM to directly measure the rate of escape of

electrons from their Coulombically bound states at electron donor–acceptor interfaces. Our

findings demonstrate that the efficiency of charge separation is determined by dynamic

competition between concerted electron-phonon

propagation versus vibrational energy

redistribution (VER). These observations

suggest that the so call ‘magic’ materials are

capable of fast electron-phonon propagation and

thus form molecularly sharp interfaces while

other materials do not. Ongoing efforts to

develop new polymers for organic solar cells

should therefore target electron donor and

acceptor pairs capable of fast electron-phonon

propagation in comparison to VER to enable

efficient separation.

References:

[1] Ryan D. Pensack and John B. Asbury, J. Phys. Chem. Letters 1 (2010) 2255.

Probing Interfacial Electron Transfer Dynamics in Photovoltaic and

Photocatalytic Nanomaterials by Time-Resolved Vibration Spectroscopy

Tianquan Lian

Department of Chemistry, Emory University, 1515 Dickey Dr. NE, Atlanta, Georgia, 30322,

USA

Understanding interfacial electron transfer dynamics is crucial to the improvement of solar

energy conversion efficiencies in photovoltaic and photocatalytic nanomaterials. In this talk,

I will discuss two recent applications of time-resolved vibrational spectroscopy to the study of

photoinduced interfacial electron transfer dynamics in these mateirals. In the first study, we

use vibrational sum-frequency generation (SFG) to probe the structure and electron transfer

dynamics of Re(Ln)(CO)3Cl (or ReCnA, Ln=2,2’-bipyridine-4,4’-(CH2)n-COOH) on rutile

TiO2 single crystals. This serves as a well-characterized model system for active components

in both dye-sensitized TiO2 solar cells and heterogeneous CO2 reduction

photoelectrochemical cells. Through combination of polarization-dependent SFG and DFT

modeling, we have determined the adsorption geometry of ReCnA molecules on the TiO2

single crystal surface. Ongoing work is focused on investigating ultrafast interfacial electron

transfer dynamics by optical pump-SFG probe spectroscopy. The measured structure and

interfacial electron transfer dynamics will be used to test modern computational methods for

modeling these systems. In the second study, we are using time-resolved IR spectroscopy to

probe the dynamics of single and multiple exciton dissociation in Quantum dots. Both

vibration spectral change of the electron acceptor and the intraband absorptions of electrons

and holes in quantum dots are probed to follow the interfacial charge transfer dynamics in

these systems. The dependence of these dynamics on the size and nature of quantum dots as

well as the energetics of the acceptors will be discussed.

AFM-Raman Imaging Analysis of Single-Molecule Interfacial Electron

Transfer Dynamics and Single-Electron Self-Exchange Fluctuations

H. Peter Lu

Bowling Green State University, Department of Chemistry and the Center for Photochemical

Sciences, Bowling Green, OH 43403; Email: hplu@bgsu.edu

Interfacial electron transfer dynamics is important for solar energy conversion and catalytic

reactions. Extensive ensemble-averaged studies have indicated inhomogeneous and complex

dynamics of interfacial ET reaction. To characterize the inhomogeniety and the complex

mechanism, we have applied single-molecule spectroscopy and correlated AFM/STM imaging

to study the interfacial ET dynamics of dye molecules adsorbed at the surface of TiO2

nanoparticles (1-6). The interfacial ET activity of individual dye molecules showed

fluctuations and intermittency at time scale of milliseconds to seconds. The fluctuation

dynamics were found to be inhomogeneous from molecule to molecule and from time to time,

showing significant static and dynamic disorders in the dynamics. Furthermore, we have

applied site-specific AFM-Raman spectroscopy on analyzing ET associated mode-specific

vibrational reorganization energy barriers and ground state single-electron self-excahnges. We

have also demonstrated a novel technical approach to probe spontaneous single electron transfer

fluctuations at molecule-substrate interfaces by probing redox state changes of the molecules.

Our experiments revealed site-to-site variations in the vibrational reorganization energy barriers

in the interfacial ET systems.

References:

1. Guo, Lijun; Wang, Yuanmin; Lu, H. Peter, "Combined Single-Molecule Photon-Stamping Spectroscopy and Femtosecond Transient Absorption Spectroscopy Studies of Interfacial Electron Transfer Dynamics," J. Am. Chem. Soc. 132, 1999-2004 (2010)

2. Yuanmin Wang, Xuefei Wang, Sujit Kumar Ghosh, H. Peter Lu, "Probing single-molecule interfacial electron transfer dynamics of porphyrin on TiO2 nanoparticles," J. Am. Chem. Soc. 131, 1479-1487 (2009).

3. Yuanmin Wang, Xuefei Wang, and H. Peter Lu, "Probing single-molecule interfacial geminate electron-cation recombination dynamics,” J. Am. Chem. Soc. 131, 9020–9025 (2009).

4. Biju, Micic, Hu, Lu, "Intermittent Single-Molecule Interfacial Electron Transfer Dynamics," J. Am. Chem. Soc. 126, 9374-9381 (2004).

5. Pan, Klymyshyn, Hu, Lu, "Tip-enhanced near-field Raman spectroscopy probing single dye-sensitized TiO2 nanoparticles," Appl. Phys. Lett., 88, 093121(2006).

6. Pan, Hu, Lu, "Probing Inhomogeneous Vibrational Reorganization Energy Barriers of Interfacial Electron Transfer," J. Phys. Chem. B, 109, 16390-16395 (2005).

Interfacial depth profiling and the effect of electric fields at a charged solid-

aqueous interface on the ultrafast vibrational relaxation of water

Ali Eftekhari-Bafrooei1 and Eric Borguet2 1 Department of Chemistry, University of California, Berkeley CA, 94720

aeftekhari@lbl.gov 2Department of Chemistry, Temple University, Philadelphia PA 19122, USA

eborguet@temple.edu

The structure of interfacial water is known to be markedly different from the bulk. One

would expect then that the vibrational dynamics, dictating the breaking and reformation of

hydrogen bonds, should be different at the interface. Our measurements of the ultrafast

vibrational relaxation of the O-H stretch at H2O/silica interfaces by vibrational sum-frequency

generation (VSFG) showed that at a negatively charged surface, where the associated electric

field extends into the bulk water, the vibrational lifetime is fast, similar to the bulk water

dynamics. However, at the neutral surface (pH~2) the dynamics is three times slower.[1]

A fundamental question that remained unanswered is whether the presence of the interface

or its chemical composition that leads to the observation of dynamics similar to bulk water at

the charged surface. We have probed the vibrational relaxation of interfacial water at a

negatively charged surface while tuning the range over which the electric field decays into the

bulk water.[2] In addition, these experiments shed light on how the interfacial thickness

varies with the ionic strength, and how the electric field affects the vibrational dynamics. Our

results support our hypothesis that the reason for faster vibrational dynamics reported by

VSFG at negatively charged surfaces is due to the penetration of the static electric field into

the bulk water, and consequent sampling of bulk-like environments. Our experiments reveal

that it is the presence of the interface, rather than whether it is charged or neutral, that

determines the vibrational dynamics.[2]

References:

[1] Ali Eftekhari-Bafrooei and Eric Borguet, Journal of the American Chemical Society 131

(2009)12034

[2] Ali Eftekhari-Bafrooei and Eric Borguet, (submitted)

Fs-2DIR-probing of the internal dynamics of supramolecular complexes

Martin Olschewski, Stephan Knop, Jörg Lindner, and Peter Vöhringer

Institute for Physical and Theoretical Chemistry, University of Bonn, 53115 Bonn, Germany

p.voehringer@uni-bonn.de

Macrocyclic polyethers, also known as “crown ethers”, are superb receptor molecules for

ionic or polar substrates that feature all fundamental phenomena of supramolecular chemistry

like self-assembly, molecular recognition, preorganization, flexibility, and induced fit. At the

same time they are still being of moderate molecular complexity so as to facilitate both,

highlevel quantum chemical and molecular dynamical calculations on the one hand and

sophisticated ultrafast nonlinear spectroscopies on the other. Here, we study the

supramolecular recognition dynamics associated with 1:1-molecular complexes of various

size crown ethers with water and alcohol substrates using femtosecond two-dimensional

infrared (2DIR) spectroscopy in the OH-stretching region of the substrate. [1-3]

The 2DIR data expose great details regarding the structural and vibrational dynamics of

the supramolecular template-substrate complexes. In particular, the delayed appearance of

highly characteristic off-diagonal signals are discussed in terms of (i) intramolecular

vibrational energy transfer within the substrate and (ii) chemical exchange dynamics that are

related to conformational transitions within the flexible receptor’s macrocycle.

Conformational transitions of the supramolecular assemblies are described as crankshaft (or

bicycle pedal) motions involving two concerted gauche-anti single-bond isomerizations on a

time scale of a few picoseconds. The experimental results are analyzed in terms of a

conformational search involving classical force field calculations followed by high-level

density functional theory, canonical transition state theory for obtaining ab initio rates, and

model simulations of the 2DIR spectra based on the non-linear response function formalism.

References:

[1] S.A. Bryan, R.R. Willis, and B.A. Moyer, J. Phys. Chem. 94 (1990) 5230.

[2] R. Schurhammer, P. Vayssière, and G. Wipff, J. Phys. Chem. A 107 (2003) 11128.

[3] M. Olschewski, S. Knop, J. Seehusen, J. Lindner, and P. Vöhringer. J. Phys. Chem. A 115,

(2011)1210.

Vibrational and electronic dynamics in correlated solid state materials

probed by time-resoled photoemission spectroscopy

Martin Wolf

Fritz-Haber-Institute of the MPG, Department Faradayweg 4-6, 14195 Berlin, Germany; email: wolf@fhi-berlin-mpg.de

The electronic properties of complex solids are often governed by strong electron-phonon

coupling and electronic correlation effects leading to phenomena like metal insulator

transitions or superconductivity and the formation of broken symmetry ground states. This

interplay between electronic and lattice degrees of freedom is of particular importance in

thermally or optically driven insulator-to-metal transitions in charge-density wave (CDW)

materials. In these materials the total energy of the system is minimized by a periodic lattice

distortion (similar to the Jahn-Teller effect) leading to an opening of an electronic gap at the

Fermi surface.

We use time- and angle-resolved photoemission spectroscopy (trARPES) to probe directly

the evolution of the electronic band structure after an ultrafast optical excitation. Using

trARPEs the collective lattice excitations become directly visible through their influence on

the band structure. We present a systematic study of a textbook CDW system (RTe3, R=Te,

Ho, Dy), a material class which exhibits a Fermi surface nesting driven CDW transition and

analyze the interplay between coherent lattice excitations and the electronic structure during

the photinduced phase transition.

Acknowledgments: Collaborations with U. Bovensiepen (U Duisburg-Essen), L. Rettig, R.

Cortes (FU Berlin), P. Kirchmann, F. Schmitt, R.G. Moore, I. Fisher and Z.-X. Shen

(Stanford U) are gratefully acknowledged

Ultrafast vibrational near-field spectroscopy Markus B. Raschke

Department of Physics, Department of Chemistry, and JILA, University of Colorado, Boulder, CO 80309, USA

With co-authors: Xiaoji Xu, Matthias Rang, and Andrew Jones E-mail: markus.raschke@colorado.edu

The strong intra- and intermolecular coupling in molecular systems is responsible for the

efficiency of the non-radiative damping compared to the radiative decay pathway in the decoherence of ultrafast vibrational excitations. Traditional coherent vibrational spectroscopy relies on nonlinear wave-mixing to probe the underlying dynamics, and often suffers from inhomogeneous spectral broadening due to ensemble averaging. While spectral hole-burning or two-dimensional ultrafast spectroscopy can obtain the homogeneous response, the correlation between spatial and temporal coherence has remained inaccessible. This includes individual nanoscale domains of heterogeneous solid state material, as reflected in a complex distribution of decoherence channels.

To address this problem, we have developed a new implementation of scattering scanning near-field optical microscopy (s-SNOM) for simultaneously nanoscale spatial and femtosecond temporal resolution. We studied the enhanced radiative far-field coupling and emission from the optical near-field of optical phonon excitation in crystalline solids and molecular vibrational excitations in block-copolymers (see Fig. 1A) as a model system. The modified tip-scattered free-induction decay transient of the coherently excited vibrational mode following a broadband femtosecond infrared excitation is temporally resolved by interferometric homodyne detection (setup see Fig. 1B). From the interferogram (Fig. 1C) we obtain the decoherence time on the nanometer scale (Fig. 1D) for a characteristic vibrational resonance. Preliminary results show a fast 200~300 fs vibrational decoherence as a result of the enhanced radiative emission due to tip-sample and near- to far-field antenna coupling in competition with the dynamics of non-radiative inter- and intra-molecular decoherence. The results demonstrate the ability of femtosecond infrared s-SNOM to provide insight into spatial coherence and inhomogeneity with nanometer spatial resolution.

Figure 1 (A) Schematic illustration of composition distribution of block co-polymer domains [1]. (B) Experimental setup (C) Extracted interferogram at one nanodomain of ps-b-p2vp block-copolymer surface. (D) Continuous red curve corresponds to extracted resonance spectrum from interferogram shown in (C). Dashed blue curve shows excitation field.

Talks Tuesday

NEW DIRECTIONS IN MULTIDIMENSIONAL OPTICAL

SPECTROSCOPY

Shaul Mukamle

Chemistry Department, University of California Irvine, Irvine, California, USA

Coherent two dimensional (2D) optical spectroscopic techniques use femtosecond laser

pulses in the infrared or visible to excite the vibrational or electronic degrees of freedom of

molecules and watch for correlated events taking place during two (or more) controlled time

intervals. Extensions into higher frequency regimes as well as novel set ups and detection

schemes that may utilize the quantum nature of light will be discussed.

Two dimensional ultraviolet (2DUV) spectra of protein backbone (far UV) and side

chains (near UV) provide new windows into the structure, dynamics and functions of

proteins. More than twenty neurodegenerative diseases are associated with the formation and

deposition of amyloid fibrils of misfolded proteins. Simulated Chirality-induced 2DUV

spectra reveal characteristic patterns of helical and sheet secondary structures that can be used

to probe the structure and aggregation mechanism of amyloid fibrils. These signals may also

be used for Identifying the Fibrillation Propensity of Protein Residue Sequences. Extensions

to the attosecond regime using x-ray pulses will be discussed. Since core excitations are

highly localized at selected atoms, such signals can monitor the motions of valence electron

wave packets in real space with atomic spatial resolution. Common principles underlying

coherent spectroscopy techniques for spins, valence electrons, and core electronic excitations,

spanning frequencies from radio waves to hard X-rays will be highlighted.

Coherent multidimensional spectroscopy of single molecules with time and frequency

gated fluorescence of photoelectron detection is proposed. Nonlinear optical signals from

single molecules are isotropic and do not allow to separate quantum pathways by looking at

different directions. However, this goal can be accomplished by examining their variation

with the phases of the pulses (phase cycling) as is routinely done in NMR.

Multidimensional signals obtained by varying the parameters of the wavefunctions of

entangled photons are discussed. The wave function of entangled photons offers additional

control parameters to the optical signals not available for classical fields. Two-photon

absorption and its variation with the entanglement time are analyzed. Spectroscopic methods

using entangled photons can show a high resolution along certain frequency axes, despite the

broad frequency band caused by the intrinsic time ordering and time correlation of the

entangled light source. Entangled photons offer an unusual combination of bandwidths and

temporal resolution not possible by classical beams.

Intermolecular Electron Density Modulations in Water Related to

Vibrational Couplings and Intensities: OH Stretching and Terahertz

Hajime Torii

Department of Chemistry, School of Education, Shizuoka University,

836 Ohya, Shizuoka 422-8529, Japan

It is well known that, for the OH stretching mode of water and alcohols, the IR intensity

and hence the dipole derivative is significantly enhanced upon hydrogen-bond formation.

However, the mechanism of this enhancement has not yet been clearly elucidated. According

to the transition dipole coupling mechanism (or its variants), the dipole derivative is important

also for mechanical coupling of OH oscillators, which leads to the resonant vibrational

excitation transport observable in the time domain as well as the corresponding spectroscopic

phenomena (called the noncoincidence effect) in the frequency domain.

In the present study, by analyzing theoretically the electron density derivative with respect

to the OH stretching mode ((el)r/QOH) [1], it is shown that this enhancement is mainly

arising from the intermolecular (rather than intramolecular) charge flux. Both the amplitude

of the electron density modulation and the distance between the charge centers are large for

this intermolecular charge flux. It is also shown that the intermolecular charge flux plays an

important role also for the intermolecular vibrational coupling of OH oscillators.

A related interesting subject is the origin of the IR intensity of the molecular translation

mode (~200 cm-1) of liquid water. It is already pointed out that the IR intensity arising from

intramolecular polarizations induced by intermolecular electrostatic (such as dipole-induced

dipole) interactions is not sufficiently strong. In the present study, the electron density

derivative with respect to the molecular translation of hydrogen-bonded water is analyzed,

and it is shown that a significant magnitude of intermolecular charge flux is also induced by

the molecular translation mode. A way to incorporate this effect in spectral simulations is also

discussed.

References:

[1] H. Torii, J. Phys. Chem. B 114 (2010) 13403.

Trpzip2 Kinetics Revealed Through Isotope-Edited Transient

Temperature-Jump 2D IR Spectroscopy

Kevin C. Jones, Joshua Lessing, Chunte Sam Peng, Andrei Tokmakoff

Department of Chemistry, Massachusetts Institute of Technology

Cambridge, Massachusetts, 02139, U.S.A., email: kcj@mit.edu

Two dimensional infrared spectroscopy (2D IR) is advantageous for the study of protein

and peptide structure and dynamics because it combines ps time resolution with the

conformational sensitivity of vibrational spectroscopy and the increased information content

inherent to a multidimensional nonlinear technique. We have combined isotope-edited amide

I 2D IR with a temperature-jump (T-jump) to reveal the conformational unfolding dynamics

of the β-hairpin peptide Trpzip2 (TZ2) from ns to ms. To provide site-specific information,

two isotopologues were synthesized to reveal changes in the mid-strand region (T3T10) and

the β-turn region (K8). Equilibrium 2D IR spectra of K8 show two turn geometries, one with

a standard Type I' β-hairpin and another with a bulged or disordered loop[1]. Improvements to

our instrument allow us to identify two distinct time-scales in TZ2's response: a <10 ns

solvation response and a 1-2 µs time scale for activated disordering of -turn structures. The

experimental results are interpreted with spectral modeling of MD simulations, which allows

us to kinetically model the shifting conformations of the heterogeneous ensemble.

Fig 1. Unlabeled TZ2 transient 2D IR difference spectra at 56 ns and 1 µs after a T-jump.

References:

[1] Smith, A.W., Lessing, J., Ganim, Z., Peng, C.S., Tokmakoff, A., J. Phys. Chem. B. 114

(2010) 10913.

Visualizing Wavepacket Dynamics through a Conical Intersection by Two-

Dimensional Electronic Spectroscopy

Niklas Christensson, Franz Milota, Oliver Bixner, Harald F. Kauffmann, Jürgen Hauer

Faculty of Physics, University of Vienna, Strudlhofgasse 4, 1090 Vienna, Austria

Two-dimensional (2D) ultrafast spectroscopic techniques open an increasingly broad

experimental window into nuclear dynamics (2D-IR) or electronic phenomena like coupling

of and transfer between electronic states in 2D electronic spectroscopy (2D-ES). By

performing 2D-ES with sub-10 fs pulses, we successfully combine the two approaches and

extract information from both degrees of freedom, electronic and nuclear, as well as their

interplay around a conical intersection (CI) in a lutetium bisphthalocyanine Lu(Pc)2- dimer.

Contrary to a simple dimer system, we observe a distinct asymmetry in the 2D spectra in

figure 1, where the cross-peak (cp) low in ω3 is missing. Following the kinetics along the

population time (t2), we find that the upper state decays on a 20 fs timescale (see diagonal

peak dp in figure 1). The relaxation goes via a vibrational state around 700 cm-1 (cp2) above

the lower diagonal peak. cp2 rises on a 10 fs timescale followed by a 160 cm-1 oscillation.

The growth of cp1 is exponential with a 60 fs time constant.

The dynamics around a CI is known to depend on the initial condition of the excited state

wave-packet. We therefore explain the pronounced asymmetry of the 2D-spectrum by a CI

and the different nuclear motions in the pathways leading to the two cross peaks. The clear

signatures of the two vibrational modes in the 2D-spectrum point to their role in the non-

adiabatic coupling dynamics through the conical intersection.

Figure 1. Electronic 2D spectra of Lu(Pc)2- for different population times on the left.

Positive (negative) features are drawn in 5% steps as full (dashed) lines. Kinetics of the

points of the 2D spectrum are shown on the right.

Nonequilibrium relaxation dynamics of vibrationally excited molecules in

liquid solution and its effect on their multidimensional infrared spectra

Name Eitan Geva1

1 Chemistry Department, University of Michigan, Ann Arbor MI, U.S.A.

Multi-dimensional infrared spectra are often modeled in terms of optical response functions.

These optical response functions consist of contributions from Liouville pathways that

correspond to sequences of impulsive field-matter interactions separated by periods of field-

free evolution. These pathways differ with respect to the chromophore’s quantum state during

the time intervals between light-matter interactions. However this formulation relies on two

key implicit assumptions, namely: (1) that the field-matter interaction is the only way to

change the state of the chromophore; (2) that the bath degrees of freedom undergo

equilibrium dynamics on the potential surface that corresponds to the chromophore’s ground

state. However, in practice irradiative relaxation processes may change the state of the

chromophore during the periods of field-free evolution and the dynamics of the bath degrees

of freedom during those time field-free periods would be dictated by the adiabatic potential

energy surfaces that correspond to the instantaneous quantum state of the chromophore. One

therefore expects the system to hop between potential surfaces during the periods of field-free

dynamics and the spectra to reflect the dynamics during the resulting inherently

nonequilibrium process.

In this talk I will describe several alternative mixed quantum-classical formulations of optical

response that are able to account for the effect of the above mentioned nonequilibrium

dynamics in a self-consistent manner. I will also demonstrate the utility of these formulations

via applications to several systems where such nonequilibrium dynamics has a profound

effect on the spectra, including (1) The hydrogen stretch of a hydrogen-bonded complex

dissolved in a dipolar liquid; (2) The hydroxyl stretch of methanol in methanol/carbon-

tetrachloride liquid mixtures; (3) The carbonyl stretches of metal-carbonyl complexes in

liquid solution.

References:

[1] Baiz, C. R., Kubarych K. J. and Geva, E., J. Phys. Chem. B (2011, in press).

[2] Hanna, G. and Geva, E., J. Phys. Chem. B 113, 9278-9288 (2009)

[3] McRobbie, P. L., Hanna, G., Shi, Q. and Geva, E., Acc. Chem. Res. 42, 1299-1309

(2009)

Water Reorientation around Amphiphiles and 2D Infrared Spectroscopy

Damien Laage1, Guillaume Stirnemann1, Fabio Sterpone1, James T. Hynes1,2

1 Ecole Normale Supérieure, Département de Chimie, 24 rue Lhomond, CNRS UMR 8640,

75005 Paris, France; 2Department of Chemistry and Biochemistry, University of Colorado,

Boulder, CO 80309-0215, USA

Many molecules of interest and importance in Chemistry and Biochemistry are

amphiphilic in character, i.e., possessing both hydrophobic and hydrophilic portions. In this

talk, we will discuss the theoretical description of the water molecule reorientation, via a jump

mechanism, in the hydration shell of such molecules in aqueous solution [1]. In particular, we

will present the mechanism’s description, and the computational support for that description,

via the Extended Jump Model whose dominant jump component addresses the ‘chemical

reaction’ of exchange of the OH of the reorienting water molecule between initial and final

hydrogen bonding partners. We especially focus on the Model’s components [2] of (a) the

Transition State Excluded Volume factor ---especially appropriate for dealing with the

hydrophobic portion---and (b) the Transition State Hydrogen Bonding factor---which

describes the influence of differing hydrogen bond strengths in the initial and final

partnership. Our focus in on, but not restricted to, the fundamental situation of dilute solution.

We will then turn to the probing of this jump mechanism and its theoretical description via

the computation of 2D infrared (2D IR) spectra for several amphiphilic molecules in aqueous

solution. Among the salient features which emerge are (a) the important but subtle aspects of

the 2D IR spectra whereby exchange of hydrogen bonds via a jump mechanism can be

responsible for water reorientational slowdown, even when the usual signatures of such

exchange are absent, and (b) the general dominance of the hydrophilic, rather than the

hydrophobic, portions of the molecules in influencing the difference of the water reorientation

time compared to that in bulk water. The relevance of these results for 2D IR experiments,

both past and future, will be discussed.

References:

[1] G. Stirnemann, J.T. Hynes, D. Laage, J. Phys. Chem. B, 114 (2010) 3052.

[2] D. Laage, G. Stirnemann, F. Sterpone, R. Rey, J. T. Hynes, Annu. Rev. Phys. Chem., 62

(2011) 395.

2D IR Spectroscopy of Water Dynamics near Hydrophobes

Maxim S. Pshenichnikov1, Artem A. Bakulin1, Christian Petersen2, and Huib J. Bakker2

1 Zernike Institute for Advanced Materials, University of Groningen, The Netherlands

e-mail: M.S.Pchenitchnikov@RuG.nl 2 FOM-institute for Atomic and Molecular Physics, Amsterdam, The Netherlands

The attractive interaction of hydrophobic molecular groups in aqueous environments plays an

essential role in the structuring and chemical reaction dynamics of biological systems.

Examples are the folding of proteins, the formation of bilipid membranes, and the interactions

between enzymes and substrates. The hydrophobic interaction is closely related to the effects

of hydrophobic solutes on the structure and dynamics of liquid water. However, neutron

scattering studies showed that hydrophobic molecular groups have in fact very little effect on

the hydrogen-bonded structure of the surrounding water [1]. In contrast, the dynamics of the

water molecules does appear to be strongly affected, as was found, for instance with NMR [2]

and 2D IR [3] spectroscopy.

Here we use 2D IR and polarization-

resolved pump-probe spectroscopy to

study the ultrafast hydrogen-bond

dynamics of water molecules interacting

with three amphiphilic solutes: tetra-butyl

alcohol (TBA), trimethyl-amine-oxide

(TMAO), and tetramethylurea (TMU).

These solutes have 3 or 4 hydrophobic

methyl groups and one hydrophilic group

arranged in a similar geometry while the

hydrophilic group is quite different. 2D IR

spectra (Fig.1b) show the substantial

slowing down of the spectral diffusion due to effect of the solutes on the hydrogen-bond

dynamics of water. The slowing down of the vibrational frequency dynamics is strongly

correlated with the slowing down of the orientational mobility of the water molecules which

indicates a common molecular origin of these effects.

References: [1] A.K. Soper, J.L. Finney, Phys.Rev.Lett. 71, (1993) 4346. [2] J. Qvist, B.J. Halle, JACS 130, (2008) 10345. [3] A.A Bakulin et al., Acc. Chem. Res. 42, (2009) 1229. [4] A.A.Bakulin et al., J.Phys.Chem.A, DOI: 10.1021/jp107881j, cover art story (2011)

Fig. 1. 2D IR spectra (2 out of ~80 in total) of pure HDO:D2O (upper) and 20% HDO:D2O solutions of TMAO (lower) at room temperature. The waiting time is set at 1 ps. The strong slowing down of the water dynamics of the solutions is represented by the elongation of the 2D spectra along the diagonal direction (right diagram).

Residue specific resolution of protein folding dynamics using time-resolved

infrared spectroscopy.

R. Brian Dyer

Emory University, Atlanta, GA USA

We have studied the molecular details of protein folding by an approach that combines

timeresolved vibrational spectroscopy with isotope editing and molecular dynamics

simulations. Our focus has been to study ultrafast folding proteins, particularly the helical

subdomain from the chicken villin headpiece (HP36), for which direct comparison between

experiment and simulation is possible. Single 13C=18O isotopic labels were incorporated into

the backbone of HP36 in each of the helices and in the connecting loops. The 13C=18O

isotopic label shifts the Amide I band ~75 cm-1 in each case, well removed from the 12C=16O

band of the unlabeled protein backbone. The unique IR signature of the 13C=18O label was

exploited to probe the equilibrium thermal unfolding transition using temperature dependent

FTIR spectroscopy. The folding/unfolding dynamics were monitored using temperature-jump

(T-jump) IR spectroscopy. The equilibrium unfolding studies showed conformational changes

suggestive of a loss of helical structure in helix 2 prior to the global unfolding of the protein.

T-jump relaxation kinetics probing both the labeled site and the 12C=16O band were found to

be biphasic with relaxation rates that strongly depend on the position within the structure. The

slow relaxation phase (~ 2x 105 s-1) corresponds to the global folding transition. The location

of the label in positions within H1 and H2 consistently gave slower relaxation times than for

labels within H3. We conclude that H3 folds faster than the two smaller helices, consistent

with what is observed in MD simulations of HP36. The significant heterogeneity in relaxation

rates observed with position of the label illustrates the complexity of the folding of this

“simple” helical structure. This heterogeneity also suggests that the folding barrier is quite

low or nearly downhill, such that we observe structure dependent folding dynamics instead of

the expected two-state behavior. Finally, the observation of the fast relaxation phase (~107 s-1)

for labeled sites that are protected from solvent (e.g. Ala57, Leu69) provides insight into the

origin of this process. The fast phase likely represents a rapid pre-equilibrium that involves

solvent penetration around the label and possible partial relaxation of individual helices prior

to the global folding/unfolding transition. In summary, this work represents the first

experimental study of ultrafast folding dynamics with residue specific resolution.

Role of Protein-Bound Water Molecules in Rhodopsins

Hideki Kandori

Department of Frontier Materials, Nagoya Institute of Technology, Nagoya, Japan

E-mail: kandori@nitech.ac.jp

Many proteins possess intra-cavities, which are often occupied by internal water

molecules, and some of them are presumed to participate in the functional process of protein.

Role of such active internal waters has been specially emphasized by structural determination

of receptors, channels, and pumps. We have studied functional water molecules in visual and

microbial rhodopsins using low-temperature light-induced difference Fourier-transform

infrared (FTIR) spectroscopy, where water O-H and O-D stretching vibrations appear at

3700-2900 cm-1 and 2700-2200 cm-1, respectively. There are so many water molecules in the

sample, but light-induced difference FTIR spectra of hydrated films can extract the signal of

such functional waters, by which important role of active internal waters has been elucidated.

I will present the history and recent topics on the protein-bound waters of rhodopsins,

including (i) strongly hydrogen-bonded water molecules (water O-D stretch in D2O at <2400

cm-1) as the functional determinant of the proton-pump function in rhodopsins, (ii) room-

temperature detection of protein-bound water signal using step-scan time-resolved FTIR

spectroscopy, and (iii) our recent attempt to measure water signal in water using attenuated

total reflection (ATR) FTIR spectroscopy.

References (Reviews):

H. Kandori, Biochim. Biophys. Acta 1460 (2000) 177; H. Kandori, Biochim. Biophys. Acta

1658 (2004) 72; H. Kandori, in cis-trans Isomerization in Biochemistry; Wiley-VCH:

Freiburg, pp 53-75 (2006); H. Kandori, in Hydrogen Bonding and Transfer in the Excited

State; John Wiley & Sons: West Sussex, pp 377-391 (2010); H. Kandori, in Supramolecular

Effects on Photochemical and Photophysical Processes; John Wiley & Sons: Hoboken, in

press (2011).

Structures of the early oligomers in the aggregation of the Alzheimer’s

peptide

Paulami Mandal, Andreas Barth

Department of Biochemistry and Biophysics, Stockholm University,

paulami012002@yahoo.co.in, andreas.barth@dbb.su.se

Alzheimer’s disease is a neurodegenerate diseases that is associated with the formation of

amyloid fibrils from the amyloid β (Aβ) peptide. Recent reports suggest that oligomers of A

are toxic to living cells [1]. Here we have followed aggregation induced by a sudden pH drop

with time-resolved infrared spectroscopy. Experiments with Aβ12-28 and Aβ1-40 indicated two

types of -sheet containing oligomers which differ in their amide I maximum, pH profile,

kinetics of formation, size and ability to grow. Protected and unprotected versions of Aβ12-28

formed antiparallel -sheets.

References:

[1] Hardy & Selkoe, Science 297 (2002) 353-356

Peptide folding dynamics studied by temperature-jump infrared-

spectroscopy combined with different isotopic substitution methods

C. Krejtschi1, O. Ridderbusch1, R. Huang2, T. A. Keiderling2, K. Hauser1,3 1 University of Frankfurt, 60438 Frankfurt, Germany

2 University of Illinois at Chicago, Chicago, Illinois 60607- 7061, USA 3 University of Konstanz, 78457 Konstanz, Germany, e-mail: Karin.Hauser@uni-konstanz.de

We analyze ns-to-µs peptide folding dynamics by time-resolved infrared spectroscopy and

laser-excited temperature jumps (~10°C). The amide I’ band provides a sensitive marker for

structural changes. However, vibrational transitions of individual amide groups are not

resolved. Isotopic editing allows variations in local structure stability to be monitored as site-

specific dynamics. We studied various single and cross-strand coupled isotopically labeled -

hairpin peptides, variants of a 12-mer tryptophan zipper whose conformation is stabilized by a

hydrophobic core formed from the interaction of four tryptophan residues. Our data supports a

multistate dynamic behavior that is consistent with a hydrophobic collapse hypothesis for

hairpin folding [1]. Although single labels do not result in spectral intensity enhancement, as

seen for cross-strand labeling, the IR frequency shifts are still diagnostic. If labels are placed

in the -strand portion of the hairpin, the observed dynamic behavior in terms of relaxation

time and activation energy closely tracks the kinetics of the -strand components. This

implies that either property, local secondary structure or cross-strand coupling enabled by

strand formation and H-bonding, relaxes with the same kinetic mechanism. However, single

labeled residues on the terminal positions are less able to be detected in contrast to the

coupled double labels at these positions. Sequence positional dependence of labels is shown

to be more discriminatory for kinetic changes than for thermodynamic variations [2].

References:

[1] K. Hauser, C. Krejtschi, R. Huang, L. Wu, T.A. Keiderling, J. Am. Chem. Soc. 130 (2008) 2984-2992.

[2] K. Hauser, O. Ridderbusch, A. Roy, A. Hellerbach, R. Huang, T.A. Keiderling, J. Phys. Chem. B (2010) 114, 11628-11637.

Mechanisms of ion-transport and selectivity in ion-channels

Ziad Ganim1, Jasper Akerboom2, Kevin Jones3, Martin Plenio3, Andrei Tokmakoff3 and

Alipasha Vaziri5

1 Physik-Department E22, Technische Universität München, Garching, Germany 2Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive,

Ashburn, VA 20147, USA 3 Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA

4Institut für Theoretische Physik, Albert-Einstein Allee 11, Universität Ulm, Germany

5 Research Institute of Molecular Pathology (IMP) and Max F. Perutz Laboratories (MFPL),

Universität Wien, Wien, Austria

Ion-channels are integral transmembrane protein complexes through which ions can flow in or out of the cell along a concentration gradient. One of the best studied classes of ion channels is the K+ channel [1]. Nevertheless, even after a number of seminal findings including the crystal structure of these channels [2, 3], it has remained a challenge to fully explain how the selectivity filter of the K+ channel can combine throughput rates as high as ~108 ions /sec [4] with a high (104:1) discrimination rate [1] between K+ and Na+. It is now believed that to understand ion selectivity and transport, one has to account for the dynamics of competing microscopic interactions. Further, it was recently suggested that an interplay between quantum coherence and environmentally induced decoherence might be involved in the ion-selectivity and transport [5]. We are using experimental strategies that allow to the dynamics of the selectivity filter with pico- to nanosecond time resolution. On one hand by resonantly driving the collective vibrational modes of the sequence of K+ions and water molecules in the selectivity filter while observing the transport rate we expect to be able to indirectly infer the presence of any vibrational coherences. On the other hand using transient 2DIR experiments we can study the structure and dynamics of the ion transport. As experimentally confirmed by the FTIR and 2DIR spectra of model molecules that mimic the coordination of different K+ and water configuration in the selectivity filter, we expect to observe transient K+ biding signatures in the amide I region. While experimental efforts in this direction are underway we have evidence based on molecular dynamics simulations (see contribution by Ganim et al.) that bound potassium increases the rigidity of the protein and causes the spectra to narrow. Although our model suggests that the different potassium ligation states should only cause subtle changes to the spectrum, we have shown that the introduction of specific combination of 13C-18O labels to enhance the signatures of different potassium-bound states. These experiments together with molecular dynamics simulations will shine new light on some of the underlying functional mechanism of the selectivity filter. References: 1. Doyle, D.A., et al., Science, 1998. 280(5360): p. 69-77. 2. Roux, B., Annual Review of Biophysics and Biomolecular Structure, 2005. 34: p.153-171. 3. Noskov, S.Y. and B. Roux, Biophysical Chemistry, 2006. 124(3): p. 279-291. 4. Gouaux, E. and R. MacKinnon, Science, 2005. 310(5753): p. 1461-1465. 5. Vaziri, A. and M.B. Plenio, New Journal of Physics, 2010. 12: p. 085001

Protein-Interactions: spatio-temporal resolved at atomic detail

Klaus Gerwert

Lehrstuhl für Biophysik, Ruhr-Universität Bochum, Bochum www.bph.rub.de

Max-Planck Partner Institute, PICB, Shanghai www.picb.ac.cn

Correspondence to Gerwert@bph.rub.de

Currently, there is a large gap between the detailed understanding of proteins in vitro and their

description in interaction pathway maps in systems biology. In order to contribute to a more

detailed understanding of protein interactions a combined approach of x-ray structure

analysis, time-resolved FTIR spectroscopy and biomolecular simulations is used.

Time-resolved FTIR difference spectroscopy can be used to monitor the reactions within

membrane proteins at atomic detail with ns time-resolution (1). This provides in combination

with structural models and biomolecular simulations (Molecular Dynamic and QM/MM) also

spatial resolution.

Furthermore the GTPase mechanism of the protooncogen Ras is investigated. The Ras protein

switches external signals to the nucleus. It is down regulated by a protein-protein interaction

with the GAP protein by catalysing the GTP hydrolysis by five orders of magnitude.

Oncogenic mutations in Ras prevent this catalysis, which results in uncontrolled cell growth

and finally to cancer. The Ras-GAP protein interaction is be studied time-resolved (2,3) Also

the surface change, which controls the protein-protein interactions with the effector

molecules, is monitored (4). In order to investigate the protein interactions closer to

physiological conditions the ATR (attenuated total reflection) technique is applied (5). This

allows to monitor the protein interaction network of the Ras superfamily spatio-temporal

resolved at atomic detail. Unpublished results of the membrane anchored Ras interaction with

effector proteins will be presented.

In addition, recent vibrational microspectroscopy (Raman and IR) studies providing

markerfree images of single cells and tissues are presented. This approach will be used to

identify cancer and neurogenerative diseases in an early state or to monitor therapy responses.

References (1) Garczarek, F., Gerwert, K. Nature 439, 109-112 (2006) (2) Kötting, C., Blessenohl, M., Suveyzdis, Y., Goody, R.S., Wittinghofer, A., Gerwert, K. Proc. Natl. Acad. Sci.USA 103, 13911-13916 (2006) (cover story) (3) Kötting, C., Kallenbach A., Suveyzdis, Y., Wittinghofer, A. Gerwert, K., Proc. Natl. Sci., 105, 17, 6260-6265 (2008) (4) Kötting, C., Kallenbach, A., Suveyzdis, Y., Eichholz, C., Gerwert, K., ChemBioChem, 8, 781-787 (2007) (5) Güldenhaupt, J., Adigüzel, Y., Kuhlmann, J., Waldmann, H., Kötting, K. and Gerwert, K., FEBS Journal, 275, 5910-5918 (2008)

Surface-enhanced IR spectroscopy of solid-supported membrane proteins

Kenichi Ataka, Ionela Radu, Melanie Nack, Henning Krassen, Joachim Heberle

Freie Universität, Experimental Molecular Biophysics, Arnimallee 14, 14195 Berlin

Membrane proteins are the target of more than 50% of all drugs and are encoded by about

30% of the human genome. Electrophysiological techniques, like patch-clamp, unravelled

many functional aspects of membrane proteins but suffer from structural sensitivity. We have

developed Surface Enhanced Infrared Difference Absorption Spectroscopy (SEIDAS) to

probe potential-induced structural changes of a protein on the level of a monolayer1,2. A novel

concept is introduced to incorporate membrane proteins into solid supported lipid bilayers in

an orientated manner via the affinity of the His-tag to the Ni-NTA terminated gold surface3.

General applicability of the methodological approach is shown by tethering photosystem II to

the gold surface4. In conjunction with hydrogenase, the basis is set towards a biomimetic

system for H2-production5. Recently, we succeeded to record IR difference spectra of a

monolayer of sensory rhodopsin II under voltage-clamp conditions6. This approach opens an

avenue towards mechanistic studies of voltage-gated ion channels with unprecedented

structural and temporal sensitivity. Initial vibrational studies on the novel light-gated

channelrhodopsin-2 (ChR2) will be presented7. ChR2 represents a versatile tool in the new

field of optogenetics where physiological reactions are controlled by light.

References:

[1] Ataka, K., & Heberle, J. (2003), J. Am. Chem. Soc. 125, 4986-4987

[2] Ataka, K., Kottke, T., & Heberle, J. (2007), Angew. Chem. Int. Ed. 122, 5544 - 5553

[3] Ataka, K., Giess, F., Knoll, et al. (2004), J. Am. Chem. Soc. 126, 16199-16206

[4] Badura, A., Esper, B., Ataka, K., et al.. (2006), Photochem. Photobiol. 82, 1385–1390

[5] Krassen, H., Schwarze, A., Friedrich, B., et al. (2009), ACS Nano 3, 4055-4061

[6] Jiang, X., Zaitseva, E., Schmidt, M., et al. (2008), Proc. Natl. Acad. Sci. USA 105,

12113-12117

[7] Radu, I., Bamann, C., Nack, M., et al. (2009), J. Am. Chem. Soc. 131, 7313-7319

Talks Wednesday

Time-Resolved and Two-Dimensional Femtsoecond Stimulated Raman

Spectroscopy

Kristina Wilson, Barbara Dunlop, Randy Mehlenbacher, David McCamant1

1 Department of Chemistry, University of Rochester, Rochester, NY 14627 USA

mccamant@chem.rochester.edu

We will highlight some of our recent results using Femtosecond Stimulated Raman

Spectroscopy (FSRS) to probe time-resolved photochemical dynamics and as a means to

impart multiple vibrational coherences for two-dimensional Raman spectroscopy.

Dimethylaminobenzonitrile (DMABN) is an achetypical charge-transfer molecule that

undergoes photoinduced intramolecular charge-transfer (ICT) in approximately 6 ps. Our

FSRS spectra (Figure 1), in combination with femtosecond transient UV-vis spectroscopy,

reveal both the rate of the ICT process in different solvents and which vibrational modes are

strongly coupled to the charge-transfer

reorganization.1 In our newly

developed technique, 2D-FSRS, an

impulsive Raman pulse imparts

vibrational coherence and a time-

delayed FSRS pulse pair reads out the

resultant Raman spectrum from ~200-

4000 cm-1.2,3 Anharmonic coupling or

nonlinear polarizability between the

initially excited modes and those

probed by the FSRS pulses can result in

the production of sidebands whose

intensity measures the coupling between the two sets of modes.

References: [1] Rhinehart, J. M.; Mehlenbacher, R. D.; McCamant, D., J. Phys. Chem. B 114 (2010),

14646. [2] Wilson, K.; Lyons, B.; Mehlenbacher, R.; Sabatini, R.; McCamant, D. M., J. Chem. Phys.

131, (2009) 214502. [3] Mehlenbacher, R.; Lyons, B.; Wilson, K.; Yong, D.; McCamant, D. M., J. Chem. Phys.

131, (2009) 244512.

Figure 1. Time resolved femtosecond stimulated Raman spectra of DMABN in methanol.

Transient Response of the OH Stretching Mode of Photoacids

Mirabelle Prémont-Schwarz1, Dequan Xiao2, Philip M. Kiefer3, Ehud Pines4, Dina Pines4,

Victor S. Batista2, James T. Hynes3,5, Erik T. J. Nibbering1

1 Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Strasse 2A,

D-12489 Berlin, Germany; 2 Department of Chemistry, Yale University, P.O. Box 208107,

New Haven, CT 06520-8107, USA; 3 Department of Chemistry and Biochemistry, University

of Colorado, Boulder, CO 80309-0215, U.S.A.; 4 Department of Chemistry, Ben-Gurion

University of the Negev, P.O. Box 653, Be’er Sheva, 84105, Israel; 5 Ecole Normale

Supérieure, Département de Chimie, 24 rue Lhomond, CNRS UMR 8640, 75005 Paris,

France.

Photoacids have been explored and utilized for decades in photoinduced proton transfer

experiments. Much less is known about the nature of photoacidity, i.e. the important increase

in acid dissociation constant with electronic excitation and its connection with the electronic

charge redistribution in e.g. the proton donating group.

We present a comparative study of the OH stretching band for several photoacid molecules in

different solvents of wide-ranging polarity, based on femtosecond infrared (IR) spectroscopy

and the quantum mechanical analysis of vibrational spectroscopic features. In the electronic

ground state we observe an OH stretching transition frequency red-shift typically associated

with hydrogen-bond (HB) formation, with the surrounding solvent also playing a significant

role. Upon electronic excitation with a UV pump pulse, the transient IR absorbance in the 2.7-

5 µm wavelength range clearly indicates a significant additional OH stretching mode

frequency decrease.

In nonpolar or weakly polar solvents without formation of a HB the OH stretch frequency

shifts of several tens of cm-1 in the electronic ground and excited states follow a relationship

governed by the solvent dielectric constant and the charge distributions of the photoacid. For

photoacid-base HB complexes in solution, OH stretching frequency shifts of several hundreds

of cm-1 are compared with known gas phase values and quantum chemical calculations to

quantify charge redistribution effects along the HB. A theoretical formulation for the solvent

polarity dependence of an HB complex’s OH stretch frequency is used to help interpret the

experimental results.

Development of Two-dimensional Electronic Femtosecond Stimulated

Raman Spectroscopy (2DE-FSRS) and its First Applications

Daniel E. Wilcox1, Franklin D. Fuller2 and Jennifer P. Ogilvie3

1 University of Michigan, Department of Physics, dewilcox@umich.edu

2 University of Michigan, Department of Biophysics, fullerf@umich.edu

3 University of Michigan, Departments of Physics and Biophysics, jogilvie@umich.edu

Two-dimensional electronic spectroscopy (2DES) has proven to be a powerful tool for

examining energy and charge transfer. However, in electronic spectroscopy the spectral

changes associated with evolving excited states are often difficult to interpret. Structural

information to complement 2DES is highly desirable. We present a novel experiment called

Two-dimensional Electronic Femtosecond Stimulated Raman Spectroscopy (2DE-FSRS) for

probing excited-state structural dynamics and their dependence on excitation energy. 2DE-

FSRS is an extension of Femtosecond Stimulated Raman Spectroscopy [1] (FSRS) where the

single actinic pump is replaced by two time-

delayed pulses, and the excitation frequency is

resolved via Fourier transform spectroscopy. A

sample 2DE-FSRS spectrum is displayed below

for Rhodamine 6G, 50fs after photoexcitation. As

reported in FSRS experiments [1], at early times

positive and negative features are seen as excited-

state Raman frequencies shift on the timescale of

the vibrational dephasing.

We present a detailed explanation of the 2DE-

FSRS implementation, which is a natural extension of 2DES with a continuum probe [2]

requiring only the addition of a Raman pump pulse. We discuss the potential for 2DE-FSRS

to probe electron-phonon coupling and present our first studies of the photoinitiated structural

dynamics of Rhodamine 6G and charge-separation in an organic photovoltaic material.

References:

[1] D. W. McCamant, P. Kukura, S. Yoon, R. A. Mathies, Rev. Sci. Instrum. 75 (2004) 4971.

[2] P. F. Tekavec, J.A. Myers, K. L. M. Lewis, J. P. Ogilvie, Opt. Lett. 34 (2009) 1390.

Figure 1: 2DE-FSRS spectrum of Rhodamine 6G in ethanol.

Dynamics at the Protein-Water Interface Revealed by 2DIR Spectroscopy

John T. King and Kevin J. Kubarych

Department of Chemistry, University of Michigan, 930 North University Avenue. Ann Arbor,

Michigan, 48109, USA

email: kubarych@umich.edu

The structural fluctuations drive protein, and since proteins dynamics are “slaved” to the

surrounding solvent, the protein-water interface plays a central energetic and dynamical role

in determining protein function.1 Experimental probes,

particularly with ultrafast time resolution and angstrom-level

spatial resolution, are generally unavailable. By complexing a

metal carbonyl vibrational probe to a surface residue of hen egg

white lysozyme (HEWL), we are able to gain unique access into

both the protein and water dynamics directly at the surface of

the protein using ultrafast two-dimensional infrared (2DIR)

spectroscopy.

In addition to its toxicity at high concentrations, CO is a

physiologically important signaling molecule. There is growing

interest in developing water-soluble metal carbonyl complexes

that can serve as sources of CO. A recent x-ray study found

specific binding of one such carbon-monoxide releasing

molecule (CORM) to HEWL.2 Here, we use this ruthenium

dicarbonyl-HEWL system to gain access to the enzyme’s dynamics including specifically the

protein-water interface. 2DIR measurements of ultrafast spectral diffusion of the complex in

H2O suggest two mechanisms for memory loss. There is an initial sub-picosecond decay

which is indicative of water dynamics occurring on the surface of the protein, followed by a

slower 5 ps decay which is attributed to the motion of flexible protein side-chains.

Additionally, binding oligosaccharides to the active site of HEWL will provide us with the

opportunity to study the non-local dynamical consequences of substrate binding as a key step

towards using 2DIR to directly probe long-range protein structure-dynamics coupling.

References:

[1] Frauenfelder H, Fenimore PW, Chen G, McMahon BH, PNAS 103 (2006) 15469-15472.

[2] Santos-Silva T, Mukhopadhyay A, Seixas JD, Bernardes GJL, Romão CC, Romão MJ, J.

Amer. Chem. Soc. 133 (2011) 1192-1195.

Figure 1. (a) Binding of CORM vibrational probe coordinated to lysozyme. (b) 2DIR spectrum of the CORM-lysozyme complex at t2 = 200 fs.

Ultrafast Raman Loss Spectroscopic (URLS) study of excited state

evolution of -terthiophene

Babita Mallick and Siva Umapathy*

Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore

560012. India, *E-mail: umapathy@ipc.iisc.ernet.in

Polythiophene (nT) is widely used in various electronic applications. Thus, an understanding

of the electron relaxation channel provides an insight into the electronic behavior that is

related to the device properties. The objective of this work is to understand the evolution and

relaxation dynamics in the initial time scales (femtosecond) of terthiophene (3T) in

cyclohexane, chosen as the model system, using time resolved Ultrafast Raman Loss

Spectroscopy (URLS)[1], a technique analogues to stimulated Raman Spectroscopy (SRS)[2].

The computational studies on 3T indicate that it undergoes a structural change from non-

planar to planar on photo-excitation. This is evident from URLS spectra recorded that are

dominated by the vibrational frequencies associated with ring deformation mode indicating

the structural rearrangement. URLS study suggests that the singlet state decays single

exponentially via the inter-system crossing into the triplet state by 650 ps. We have also

studied the effect of resonance on URLS signal by varying Raman excitation wavelength

within the absorption spectrum of the transient. URLS signal line shape is found to change

from negative to positive via dispersive form. We believe, alike in the resonance Raman (RR)

studies, this unique pattern observed traces the level of Franck Condon activity of a particular

mode within the absorption spectrum at those wavelengths. Further work in this regard is

being carried out. Based on this study and our earlier reports [1], we propose the ideal

conditions for resonance Raman experiments under URLS/SRS.

References

[1] S. Umapathy, A. Lakshmanna. and B. Mallick J. Raman Spectrosc. 40 235 (2009); A.

Lakshmanna, B. Mallick and S. Umapathy Current Science 97 210 (2009); S.

Umapathy, B. Mallick and A. Lakshmanna, J. Chem. Phys. 133 024505 (2010).

[2] B. Mallick, A. Lakhsmanna, V. Radhalakshmi and S. Umapathy Curr. Sci. 95 1551

(2008); P. Kukura, D.W. McCamant, and R.A. Mathies, Annu. Rev. Phys. Chem. 58 461

(2007); S. Laimgruber, H. Schachenmayr, B. Schmidt, W. Zinth and P. Gilch, Appl.

Phys. B 85 557 (2006).

Femtosecond vibrational study of water dynamics in salt solutions

H.J. Bakker, K-J. Tielrooij, N. Garcia-Araez, M. Bonn

FOM Institute AMOLF, Kruislaan 407, 1098 SJ Amsterdam, The Netherlands

bakker@amolf.nl

We study the orientational mobility of water in the hydration shells of ions with

polarization-resolved femtosecond mid-infrared spectroscopy (fs-IR) and terahertz (THz)

time-domain spectroscopy (THz-TDS). These two techniques probe the reorientation of

different axes of the water molecule, thus providing detailed insight in the molecular

reorientation of solvating water. In the fs-IR experiments the OD stretch vibration is excited

with intense 100 fs pulses at 4 m. The anisotropy dynamics represents the reorientation of

the OD group of HDO molecules dissolved in H2O. In the THz-TDS studies, we determine

the reorientation of the dipole moment p of the water molecule, i.e. the bisector of the water

molecule, by probing the polarization response of the solution to a far-infrared electric field.

For solutions containing cations that strongly interact with water, like Mg2+, we observe a

significant depolarization effect with THz-TDS, corresponding to 6 slow H2O, and a

negligibly small effect with fs-IR (Fig. A). In contrast, for solutions containing anions that

strongly interact with water, like SO42-, we observe little effect with THz-TDS, corresponding

to only 1 H2O, and a pronounced slowing down of the reorientation of the hydrating water

molecules with fs-IR (Fig. B). These results show that water molecules in the hydration shells

of ions are strongly hindered in their orientation mobility, but only in certain directions.

Interestingly, we observe that some cation and anion combinations, such as MgSO4, can

impede the motions of many water molecules at relatively long ranges. We observe ~18 slow

H2O per Mg2+ and SO42- (Fig. C) [1]. This number is much larger than expected from the sum

of the contributions of the separate cations and anions, showing that the effects of ions on the

dynamics of water can be highly non-additive.

References:

[1] K.-J. Tielrooij, N. Garcia-Araez, M. Bonn, and H.J. Bakker, Science 238, 1006 (2010).

Comparison of Frequency Fluctuation between the Vibrational State and

Electronic State in Aqueous Solution

Keisuke Tominaga1,2, Junpei Tayama1, Akina Kariya2, Mami Takatsuka2, Akane Ishihara2,

Motohiro Banno1, Kaoru Ohta1,3, Shinji Saito4, and Seiji Akimoto1,2

1Molecular Photoscience Research Center, Kobe University, Kobe, Japan 2Graduate School of Science, Kobe University, Kobe, Japan

3PRESTO, JST, Japan 4Institute for Molecular Science, Okazaki, Japan

e-mail: tominaga@kobe-u.ac.jp

Liquid water forms three-dimensional hydrogen bonding network, which continuously repeats

formation and breaking of the hydrogen bonds as well as structural fluctuation of the network.

Such a fluctuation of the network causes large changes in the vibrational and electronic states

of a solute molecule. In this work we obtained time correlation function (TCF) of frequency

fluctuation of both the vibrational and electronic states to compare them in light of theoretical

prediction using the dielectric relaxation data. We especially focus on temperature

dependence and isotope effect on both the frequency fluctuations. As for the electronic state,

we performed dynamics fluorescence Stokes shift experiment using an ionic coumarin dye

molecule as a probe. The response function of the dynamic Stokes shift is proportional to the

TCF of the frequency fluctuation within the linear response theory. The response function is

characterized by a bi-exponential function with a ~200 fs component and about ~1.2 ps

component at room temperature. The vibrational frequency fluctuations were studied by

three-pulse IR photon echo technique [1]. It is found that the TCF can be expressed in terms

of a bi-exponential function with ~100 fs and ~1.5 ps components. We found that this

picosecond component does not depend on the solute molecule so much. Furthermore, there is

a small difference in this component between H2O and D2O. When temperature is changed

from 283 K to 353 K, the picosecond component changes from 1.4 ps to 1.1 ps. We will

discuss relation between this component and the dielectric relaxation.

References:

[1] J. Tayama, A. Ishihara, M. Banno, K. Ohta, S. Saito, and K. Tominaga, J. Chem. Phys.

133, 014505 (2010).

Talks Thursday

Formation of DNA photolesions resolved by transient IR-spectroscopy.

W. Zinth1, K. Haiser1, J. Kubon1, W. J. Schreier1, B. Pilles1, P. Gilch1, G. Ryseck1,

B. Fingerhut2, R. de Vivie-Riedle2, K. Heil2 and T. Carell2 1 BioMolekular Optics, Ludwig-Maximilians-University Munich, Oettingenstraße 67, 80538

Munich (Germany)

wolfgang.zinth@physik.uni-muenchen.de 2Department Chemie, Ludwig-Maximilians-University Munich , Butenandt-Straße 11, 81377

Munich

Ultraviolet (UV) radiation induces a number of different photo-damages in DNA. Among

them the CPD (cyclobutane pyrimidine dimer) photolesion of neighbouring thymine bases is

most abundant while the Dewar valence isomer is most serious. In this contribution we use

time resolved UV-pump, IR-probe-spectroscopy to study the formation dynamics of these

photolesions. We will present results from different model systems (dimers, modified dimers,

longer single strands). The experiments reveal that the formation of the CPD lesion occurs

within ~ 1ps, i. e. during the ultra-rapid decay of the excited singlet state. For this reaction a

favourable arrangement of the adjacent thymine molecule is prerequisite and variations of the

arrangement influence the quantum efficiency.

Illumination of the T(6-4)T lesion – the precursor of the Dewar isomer – with light at 320 nm

populates an excited electronic state which lives for ~ 100 ps. Within 2.5 ps after optical

excitation the molecule reaches a local minimum on the excited electronic landscape. The

subsequent decay of the excited electronic state is much slower and depends on temperature.

The formation of the Dewar valence isomer is followed via the IR absorption of the C=O

stretching mode, which is located at 1781 cm-1. The IR experiment directly shows that the

formation of the Dewar photolesion occurs upon the decay of the excited singlet states. The

combination of experimental investigations with quantum chemical simulations allows to

obtain detailed information on the molecular coordinates promoting lesion formation and

shows that the connection of the two thymine molecules via the backbone is prerequisite for

Dewar formation.

References: [1] W.J. Schreier, T.E. Schrader, F.O. Koller, P. Gilch, C.E. Crespo-Hernandez, V.N. Swaminathan, T. Carell, W. Zinth, B. Kohler, Science 315 (2007) 625. [2] W. J. Schreier, J. Kubon, N. Regner, K. Haiser, T.E. Schrader, W. Zinth, P. Clivio, P. Gilch, J. Am. Chem. Soc. 131 (2009) 5038.

The Photo-Induced Decarboxylation of Nitrophenylacetates

Wachtveitl, J.1, Neumann, K.1, Verhoefen, M.-K.1, Mewes, J.-M.1, Wille, G.2, Dreuw, A.1

1Institute of Physical and Theoretical Chemistry, Goethe University, Frankfurt, Germany

2Institute of Biophysics, Goethe University, Frankfurt, Germany

wveitl@theochem.uni-frankfurt.de

Photo-labile protecting groups allow for light-triggered release of chemically or

biologically active compounds with unique spatial and temporal control, a process commonly

called uncaging. The most prominent structural motif in modern caged compounds is the

ortho-nitrobenzyl (o-NB) group, whose photochemistry is subject of research already since

1901.[1] We investigated the photo-induced decarboxylation (PDC) of all three constitutional

isomers of nitrophenylacetate (NPA), which can be regarded as caged-CO2. Ortho-NPA (o-

NPA) exhibits a quantum yield of only 4% with respect to CO2 release, whereas meta- (m-

NPA) and para-NPA (p-NPA) have quantum yields of 63% and 59%, respectively.[2] UV-

pump / IR-probe spectroscopy was used to directly observe the nascent CO2 in the region of

2340 cm-1. Together with quantum chemical calculations the reaction models for all three

components could be obtained.[3] For m- and p-NPA the main decarboxylation pathway

proceeds via the triplet state with a life time of 0.2 ns. In case of o-NPA the PDC reaction is

suppressed by an H+- or H•-transfer reaction due to the proximity of the nitro- and acetate-

substituents. Nevertheless, the PDC can be investigated due to the isolated spectral position of

the CO2 band. The analysis of the data reveals that a weak ultrafast release channel (< 300 fs)

represents the main PDC reaction pathway for o-NPA. The very slow consecutive reactions of

the nitrobenzyl anion of p-NPA and the low PDC quantum yield o-NPA reduce their

applicability, but m-NPA is an ideal component that can be utilized as caged CO2.

Furthermore, the detailed understanding of the molecular mechanisms of CO2 uncaging

should provide general guidelines for the design of systematically improved NB cages.

References:

[1] P. Silber, G. Ciamician, Chem. Ber. 43 (1901) 2040.

[2] J. D. Margerum, C. T. Petrusis, J. Am. Chem. Soc. 91 (1969) 2467.

[3] J.-M. Mewes, K. Neumann, M.-K. Verhoefen, G. Wille, J. Wachtveitl, A. Dreuw (2011),

submitted.

Ultrafast vibrational dynamics of parallel excited state proton transfer reactions in the Green Fluorescent Protein

Jasper J. van Thor1*, Arthur McClelland2, Brendon Kellner2, Craig N. Lincoln1, Konstantinos N. Bourdakos1, Mike Bearpark3, J. Timothy Sage2, Paul M. Champion2.

1 Division of Molecular Biosciences, Imperial College London, South Kensington Campus, London SW72AZ, United Kingdom, 2 Department of Physics and Center for Interdisciplinary

Research on Complex Systems, Northeastern University, Boston, Massachusetts 02115, 3Department of Chemistry, Imperial College London, South Kensington Campus, London

SW72AZ, United Kingdom, *e-mail: j.vanthor@imperial.ac.uk.

The Green Fluorescent Protein (GFP) is unique to show Excited State Proton Transfer (ESPT) in a protein environment, providing a directional coordinate for the ultrafast proton transfer reactions rather than disorder liquids1,2. ESPT proceeds on a picosecond time scale and we report on the vibrational response and coherence of the chromophore and the protein environment during the time scale of this reaction. A direct relationship between equilibrium protein side-chain conformation of glutamate 222 and reaction kinetics is established for the ultrafast ESPT in the fluorescence photocycle. We show that parallel transformations in the photocycle have a structural origin and establish assignment of antisymmetric and symmetric stretching modes of the excited state proton acceptor group, the E222 carboxylate on the basis of analysis of transient IR data from an E222D mutant 3,4,5. Pump-dump-probe spectroscopy further addresses the heterogeneous nature of ESPT. We additionally discuss photoselection measurements 6. for the molecular interpretation of the vibrational transition dipole moments placed in the X-ray frame as a sensitive probe of the mode character and asses the assignments based on frequency calculations from the analytical second derivative for the isolated chromophore 5. and high level multi-layer ONIOM calculations that allows the inclusion of electrostatic and mechanical embedding of the protein environment 7. We further present results of the vibrational response of GFP using Vibrational Coherence Spectroscopy (VCS), which identifies a number of low frequency vibrational coherences at cryogenic and ambient temperatures that decay on a picosecond time scale8,9. These ‘soft’ modes, below kT=200 cm-1, are easily thermally populated and the associated distortions are thought to play a role in the ESPT reaction 10. References: [1] J. J. van Thor, Chem. Soc. Rev. 38, 2935-2950 (2009). [2] M. Chattoraj, B. A. King, G. U. Bublitz and S. G. Boxer, Proc. Natl. Acad. Sci. U.S.A. 93, 8362-8367 (1996). [3] J. J. van Thor, G. Y. Georgiev, M. Towrie and J. T. Sage, J. Biol. Chem. 280, 33652-33659 (2005). [4] J. J. van Thor, G. Zanetti, K. L. Ronayne and M. Towrie, J. Phys. Chem. B 109, 16099-16108 (2005). [5] van Thor, J.J., Roynane, K.L., Towrie, M., J.T. Sage (2008) Biophysical Journal. 95, 1902-1912 [6] L.J.G. van Wilderen, C. N. Lincoln and J.J. van Thor. PLOS ONE. In press. doi 10.1371/journal.pone.0017373 (2011) [7] M. Bearpark, L. Thompson, J.J. van Thor. In prep (2011) [8] A. McClelland, A. Demidov, A. Benabbas, Y. Sun, K. Venugopal, J.T. Sage, J. J. van Thor and P. Champion. AIP Conf. Proc. 1267, 674-675 (2010) [9] A. McClelland, A. Demidov, A. Benabbas, Y. Sun, K. Venugopal, J.T. Sage, J. J. van Thor and P. Champion. In prep (2011) [10] C. Fang, R. R. Frontiera, R. Tran and R. A. Mathies, Nature 462, 200-204 (2009)

Watching energy flow in hemeproteins

Yasuhisa Mizutani1, Naoki Fujii1, Misao Mizuno1, and Haruto Ishikawa1

1Department of Chemistry, Graduate School of Science, Osaka University

mztn@chem.sci.osaka-u.ac.jp

Flow of excess energy from a reacting molecule is one of the key issues for understanding

how chemical reactions take place in the condensed phase, such as liquid and protein. Excess

energy is often deposited in many degrees of freedom right after photoreactions or internal

conversions. Many experiments have been performed to study the dissipation processes of

excess energy after photoexciting the chromophores. Particularly, heme proteins have been

extensively studied because the heme exhibits ultrafast internal conversion. The cooling

processes of the heme [1] and the heating of solvent molecules [2] have been well

characterized by ultrafast spectroscopy. However, the energy migration within protein moiety

has not been directly observed. In this study, we succeeded in observing the vibrational

energy migration in photoexcited heme proteins by using anti-Stokes ultraviolet resonance

Raman (UVRR) spectroscopy.

UVRR spectroscopy can selectively monitor Raman bands of aromatic amino acid

residues, such as tryptophan (Trp), tyrosine (Tyr), and phenylalanine (Phe). Anti-Stokes

Raman intensity reflects the population in vibrationally excited states. Therefore, anti-Stokes

UVRR intensity can be a direct probe of vibrational energy of residues in a protein. We

measured time-resolved anti-Stokes UVRR spectra of myoglobin upon the excitation of heme.

Anti-Stokes bands attributed to the Trp residue at 760 (W18 band) and 1012 cm-1 (W16 band)

were observed. These bands grew in a few picoseconds and diminished in tens of

picoseconds. The increase and decrease of band intensities can be ascribed to energy transfer

from the heme and energy release to the surrounding residues, respectively. Site-directed

mutagenesis enabled us to introduce a Trp residue at the desired position. We investigated

distance dependence of energy flow from the heme and discuss the energy transport

mechanism in protein moiety.

References:

[1] Mizutani and Kitagawa, Science 278 (1997) 443-446.

[2] Lian et al., J. Phys. Chem. 98 (1994) 11648-11656.

Ultrafast Infrared and Stimulated Raman Spectroscopy of Biomolecules

John T.M. Kennis1

1 Department of Physics, VU University Amsterdam, j.t.m.kennis@vu.nl

(i) BLUF domains constitute a recently discovered class of photoreceptor proteins sensitive to

blue light through a FAD cofactor that is involved in an extensive hydrogen-bond network

with nearby amino acid side chains, including a highly conserved tyrosine and glutamine. The

participation of particular amino acid side chains in the ultrafast hydrogen-bond switching

reaction with FAD that underlies photoactivation of BLUF domains was assessed by means of

ultrafast infrared spectroscopy. Blue-light absorption by FAD results in formation of FAD•-

and a bleach of the tyrosine ring vibrational mode on a picosecond timescale, showing that

electron transfer from tyrosine to FAD constitutes the primary photochemistry. Subsequent

protonation of FAD•- to result in FADH• on a picosecond timescale is evidenced by the

appearance of a N-H bending mode at the FAD N5 protonation site and of a FADH• C=N

stretch marker mode, with tyrosine as the likely proton donor. FADH• is reoxidized in 67 ps to

result in a long-lived hydrogen-bond switched network around FAD. This hydrogen-bond

switch shows infrared signatures from the C-OH stretch of tyrosine and the FAD C4=O and

C=N stretches, which indicate increased hydrogen-bond strength at all these sites. The results

support a rotation of glutamine by 180o through a light-driven radical pair mechanism as the

determinant of the hydrogen-bond switch.

(ii) A new wavelength modulator based on a custom-made chopper blade and slit placed in

the Fourier plane of a pulse shaper was used to explicitly detect the first derivative of the

time-resolved femtosecond stimulated Raman signal (FSRS). This approach resulted in a

significant reduction of the nonresonant background inherent to FSRS experiments. The

method was demonstrated for β-carotene where the FSRS signatures of the optically allowed

S2 state and the optically forbidden S1 state are reported.

Engineering Femtosecond Chemistry for the Development of Efficient

Organometallic Photochromes

Karen MOSLEY1, Jermaine JOHNSON1, James BARR,1 Charles Edwin WEBSTER1 Theodore J. BURKEY1 and Edwin J. HEILWEIL2

1Department of Chemistry, The University of Memphis, Memphis,38152-3550, USA; 2National Institute of Standards and Technology, Gaithersburg, 20899-8443, USA;

E-mail: tburkey@memphis.edu We prepare photochromic materials based on organometallic complexes that can undergo light-

driven linkage isomerization (Scheme 1) where the isomerization involves the interconversion of two chelates (To et al., 2009). Our studies include the effect of functional groups A and B, the link between them and the bridge between the metal and A and B. Chelation following ligand dissociation competes with ligand recombination and solvent coordination. Chelation is found to occur on two timescales: (1) sub-picosecond reaction that competes with ligand recombination and solvent coordination. In some cases the chelation occurs to the exclusion of both ligand recombination and solvent coordination even when a solvent makes stable bonds with the metal center (To et al., 2006). (2) on the 100 ns timescale for species in alkanes and longer in more reactive solvents. The latter timescale is the result of ultrafast solvent coordination where solvent must be displaced for chelation to occur. Since ultrafast solvent coordination and ligand recombination can lead to unproductive processes and delays for light driven molecular devices it is important to understand how they can be eliminated.

In the case of 1, a photochrome is produced based on two linkage isomers with blue (2) and purple (3) chromophores (Scheme 2). 2 is unstable at room temperature, and rearranges to 3 within 5 min but can be reversed by irradiation with visible light (To et al., 2006). Along with the stability of the linkage isomers, an important question in the development of photochromic materials is to what extent both isomers are formed directly from an excited state as opposed to isomerization following irradiation. This directly addresses issues of quantum yields and the efficiency of the photochromic response. We have prepared several analogs of 1 (Scheme 3) and investigated them in heptane with steady-state, ultrafast time-resolved infrared (TRIR), and computational methods.

In most cases, chelates with X are unstable unless Y and Z = CH. When both X and Y are both heteroatoms both chelates are formed within 100 ps but the distribution depends on side chain structure. In general, ultrafast solvent coordination is excluded. The results indicate that 8 is the only compound that is bistable and suggests that ultrafast chelation is favored by side-chain conformations that predispose the function group near the metal center.

To TT, Heilweil EJ, Ruddick KR, Webster CE, Duke III CB, Burkey TJ. 2009. The

development of ultrafast photochromic organometallics and photoinduced linkage isomerization of arene chromium carbonyl derivatives. Journal of Physical Chemistry A, 113: 2666-2676.

To TT, Heilweil EJ, Burkey TJ, 2006. Time-resolved infrared absorption study of cyclopentadienyl manganese tricarbonyl derivatives: chelation of pendant sulfides in acetonitrile. Journal of Physical Chemistry A 110: 10669-10673.

To TT, Duke III CB, Junker CS, O'Brien CM, Ross CR, Barnes CS,Webster CE, Burkey TJ 2008. Organometallics 27: 289-296.

Scheme 2.

Scheme 1

Scheme 3

Conversion of light into chemical energy: Electron transfer processes in

Photosystem I and the bacterial reaction center-light harvesting 1 complex.

Marloes Groot1, Mariangela Di Donato1, Andy D. Stahl1, Mike Jones2

1 Faculty of Sciences, Department of Physics and Astronomy, VU University Amsterdam, NL

2 Department of Biochemistry, School of Medical Sciences, University of Bristol, UK

Vibrational spectroscopy is an extremely valuable tool in the study of photosynthesis, as

the signatures of cation, anion and electronically excited chlorophyll states are much more

distinct from each other in the midIR spectral region than in the visible spectral region. Earlier

[1] we used femtosecond IR spectroscopy to reveal the identity of the initial electron donor

and acceptor in reaction centers of Photosystem II. Here, we studied Photosystem I, one of

the key players in the conversion of solar energy into chemical energy. While the chlorophyll

dimer P700 has long been identified as the primary electron donor, the components involved

in the primary charge separation process in PSI remain undetermined. Our data reveals cation

signals on a subpicosecond time scale (0.8-1 ps) indicating ultrafast formation of the primary

radical pair. Modeling of the data allows us to extract the spectra of this and the secondary

radical pair, and to conclude that the cofactor chlorophyll A acts as the primary donor in PSI.

Next, we studied the characteristics of charge separation in intact RC-LH1 complexes from

bacteria. We were particularly interested in whether the LH1 pigment-protein environment

modulates the characteristics of charge separation as, for example, there is evidence that the

mid-point redox potential for oxidation of the P dimer is modulated by the antenna

environment, being ~50 mV lower in intact native membranes than in antenna-deficient

membranes or isolated RCs. In addition we studied the mechanistic basis for the loss of

photosynthetic competence that accompanies removal of PufX, a single membrane-spanning

α-helix which has a strong influence on the structure of the RC-LH1 complex.

References:

[1] M.L. Groot, N. P. Pawlowicz, L. van Wilderen, J. Breton, I. H. M. van Stokkum and R.

van Grondelle, Proc. Natl. Acad. Sci. USA 102 (2005) 13087-13092

Selecting the structural resolution: 2D IR spectroscopy and native chemical ligation

Sean D. Moran1,2, Ann M. Woys1, David Skoff1, Eli Bixby2,

Sean M. Decatur2, and Martin T. Zanni1 1University of Wisconsin-Madison, Madison, WI, USA.

2Oberlin College, Oberlin, OH, USA.

The infrared spectra of proteins is remarkably sensitive to structure. However, in even

small proteins, the spectra become so congested that different pieces of the protein cannot be

resolved from one another. One way to regain structural specificity is to isotope label a single

amino acid, which our group and others have used to much success. However, in proteins

larger than a few dozen amino acids, it is synthetically difficult to isotope label a single

residue. Non-natural amino acids can be used, such as cyanophenyl groups, but their infrared

transition dipole strengths are weak. In this talk, I will present a new approach to gain

structural specificity with infrared spectroscopy. We have used uniform 13C labeling via

protein expression and native chemical ligation in order to isotopically label one of two

domains in the cataract-related lens protein, human D-crystallin. D-crystallin is an 174

amino acid protein composed of two Greek key domains. When isotope labeled, we are able

to individually resolve the two domains. Various 2D IR equilibrium and kinetics experiments

will be presented, in which we have explored the mechanism by which this protein forms

amyloid fibers that are thought to be a component of cataracts. This labeling techniques

provide an entirely new avenue for using infrared spectroscopy to study protein structure that

we believe will be especially valuable for studying systems that are not easily accessible using

standard structural biology techniques.

H-bond Switching and Ligand Exchange Dynamics in Aqueous Ionic

Solution

Kelly J. Gaffney1, Minbioa Ji2, Zheng Sun3

1 SLAC National Accelerator Laboratory, Stanford University kgaffney@slac.stanford.edu

2 Department of Chemistry and Chemical Biology, Harvard University minbiaoj@google.com

3SLAC National Accelerator Laboratory, Stanford University sz3288@stanford.edu

Aqueous ionic solutions lubricate the chemical machinery of the environment and life.

Understanding the impact of ions on the properties of aqueous solutions and how these

modified properties influence chemical and conformational dynamics remains an important

and elusive objective of physical chemistry research. The talk will focus multidimensional

vibrational spectroscopy studies of (1) the dynamics and mechanism of H-bond switching in

concentrated aqueous sodium perchlorate solutions [1-3] and (2) the dynamics and

mechanism of ligand exchange around alkali earth cations in aqueous ionic solutions [4].

References:

[1] S. Park, M. Odelius, K.J. Gaffney, J. Phys. Chem. B 113 (2009) 7825.

[2] M.B. Ji, M. Odelius, K.J. Gaffney, 328 (2010) 1003.

[3] M.B. Ji, K.J. Gaffney, 134 (2011) 044516.

[4] S. Park, M.B. Ji, K.J. Gaffney, 114 (2010) 6693.

The Role of CN and CO Ligands in the Vibrational Relaxation Dynamics of

Model Compounds of the [FeFe]-Hydrogenase Enzyme

Spyridon Kaziannis,a Joseph A. Wright,b Marco Candalaresi,a Rafal Kania,a Gregory M.

Greetham,c Anthony W. Parker,c Christopher J. Pickett,b and Neil T. Hunta

a E-mail: nhunt@phys.strath.ac.uk, Dept. of Physics, University of Strathclyde, SUPA, 107

Rottenrow East, Glasgow, UK; b Energy Materials Laboratory, School of Chemistry,

University of East Anglia, Norwich, UK c Central Laser Facility, STFC Rutherford Appleton

Laboratory, Didcot, Oxon, UK

The vibrational dynamics of (µ-propanedithiolate)Fe2(CO)4(CN)22-, an active site model of

the [FeFe]-hydrogenase enzyme have been examined using 2D-IR spectroscopy. The results

indicate that vibrational coupling between the stretching modes of the CO and CN ligands is

small and mode-specific. Slow growth of off-diagonal peaks is assigned to complex

population transfer processes occurring between these modes on timescales of 30-40ps.

Analysis of the data using anharmonic DFT calculations shows that the presence of CN

ligands alters the relaxation dynamics of the CO modes in comparison to all-carbonyl systems

and suggest that the presence of these ligands in the enzyme may be an important feature in

terms of the vibrational relaxation mechanism.

:

1 8 5 0 1 9 0 0 1 9 5 0 2 0 0 0 2 0 5 0 2 1 0 0

2050

2100

2075

1840 1880 1920 1960 2000 2040 2080

1840

1880

1920

1960

2000

2040

2080

-1.1

-1.0

-0.95

-0.86

-0.77

-0.68

-0.59

-0.50

-0.41

-0.32

-0.23

-0.14

-0.054

0.13

0.21

0.30

0.39

0.48

0.57

0.66

0.755 ps

50 ps

Probe Frequency (cm-1)

Pu

mp

Fre

qu

en

cy

(cm

-1)

Fig 1: 2D-IR spectrum of (µ-propanedithiolate)Fe2(CO)4(CN)22- at two delay times showing

slow growth of off-diagonal features.

The Dynamic Signature of the Enzymatic Transition State Probed by 2D IR

Spectroscopy

Christopher M. Cheatum

Department of Chemistry and Optical Science and Technology Center, University of Iowa,

Iowa City, Iowa 52242

Understanding the structural and dynamic characteristics of enzymatic transition states is

central to enzymology and underlies much of the efforts to rationally design pharmaceuticals

that target specific enzymes, and 2D IR spectroscopy has proven to be a powerful tool for

characterizing the active-site dynamics of enzymes at the femtosecond to picosecond

timescale. We report 2D IR studies of the NAD+-dependent enzyme formate dehydrogenase

(FDH) for which the azide anion is a transition-state-analog inhibitor. The ternary complexes

of FDH with azide and NAD+ or NADH exhibit unusually fast dynamics that suggest a very

rigid structure. To extend on these studies we have synthesized an NAD+-analog, PAAD,

where an azido group has been substituted on the cofactor to provide a spectroscopic handle

with minimal perturbation to the system. We characterize the dynamics of the complex of

FDH with this cofactor and azide showing that it causes only minor perturbations of the

structural fluctuations as compared to the natural coenzyme. Then, using PAAD, we measure

the dynamics of a series of inhibitors to compare the fluctuations of the ternary complex with

the transition state analog, azide, to the motions when other inhibitors are present. Based on

our results, we conclude that the transition state complexes of enzymes exhibit rigid structures

that sample a narrow distribution of conformations on fast time scales and that this rigidity is

a dynamic signature of the transition state complex. In addition, the development of our new

spectroscopic probe opens the possibility for further studies of this sort using a wide range of

NAD+- and NADP+-dependent enzymes.

Electron Delocalization in the Singlet and Triplet States of MM (M = Mo or

W) Quadruply Bonded Complexes Supported By Carboxylate and

Amidinate Ligands

Brian G. Alberding1, Malcolm H. Chisholm1, and Terry L. Gustafson1

1 The Ohio State University, Department of Chemistry, gustafson@chemistry.ohio-state.edu

The compounds studied have the general molecular formula trans-M2(X2C-L)2(X2CL’)2

(below), where M = Mo or W, X = NiPr or O, and L and L’ represent organic groups.

Compounds of this type are known to possess low energy states that can be described as

metal-to-ligand charge transfer (MLCT) or metal-centered (δδ*) in both the singlet and triplet

manifolds where the ording of these states depends strongly on the nature of the chosen metal

and the ligand organic π-conjugation.1,2 Femtosecond time-resolved infrared spectroscopy

(fsTRIR) has been used to verify the assignments of the lowest energy singlet and triplet

states and also to elucidate the extent of charge delocalization within these states. In

particular, the fsTRIR experiments have utilized probe regions characteristic of both L-bound

IR reporter groups as well as the CN2 or CO2 vibrations inherent to the ligands to make these

assignments. Furthermore, DFT calculations of neutral and singly reduced model systems

have been used to simulate the vibrational spectra of the ground and excited state compounds,

respectively, and support the results.

Time-resolved Studies of Isomerization and Vibrational Relaxation in

Liquids and Cryogenic Matrices

T. J. Preston1, Scott A. Reid2, and F. F. Crim3

1 University of Wisconsin - Madison, tjpreston@wisc.edu

2 Marquette University, scott.reid@marquette.edu

1 University of Wisconsin - Madison, fcrim@chem.wisc.edu

Photodissociation and recombination of haloalkanes in solution can produce a relatively

weakly bound isomer, formed by the return of the departing halogen atom to bind to another

halogen atom in the radical fragment rather than to the carbon from which it departed. For

example, the 266-nm photolysis of neat bromoform (HCBr3) produces isobromoform (HCBr2-

Br), some of which dissociates to release Br atoms into solution.[1] The time evolution in

mixtures of bromoform and cyclohexane is similar to that in pure bromoform. The initial 13-

ps decay of the isomer likely corresponds to the period during which the isomer retains

enough vibrational energy to break its weakest bond to release a Br atom.

Now it is possible to follow such an isomerization in the rather different environment of a

cryogenic matrix. Building on spectroscopy of such isomers in Ar matrices, we have

photolyzed chloroiodomethane (H2CICl) and observed the time evolution of the iso-

compound, H2CCl-I, formed by the caging and return of the departing I. A key to these

experiments is using a separate pulse to convert the product back to reactant after each

excitation pulse.[2] The time-evolution observed in different portions of the electronic

absorption band of the isomer suggests that the first collision of the atom with the cage

transfers substantial amounts of energy and that the partially relaxed isomer loses its

remaining vibrational energy in about 30 ps.

References:

[1] S. L. Carrier, T. J. Preston, M. Dutta, A. C. Crowther, and F. F. Crim, J. Phys. Chem. A

114 (2010) 1548.

[2] R. Schanz, V. Bolan, and P. Hamm, J. Chem. Phys. 122 (2005) 044509.

Nonlinear THz spectroscopy and coherent THz control

Keith A. Nelson

MIT Department of Chemistry, Cambridge, MA 02139 USA, kanelson@mit.edu

In recent years it has become possible to generate intense THz pulses with microjoule

energies and peak field strengths approaching or exceeding 1 MV/cm [1]. The THz pulses are

generated as coherent phonon-polariton waves inside ferroelectric crystals, mainly lithium

niobate (LN). The pulses may be delivered to a sample of interest directly in contact with a

bulk or waveguide LN crystal, or the electromagnetic part of the phonon-polariton wave may

be coupled out of the crystal into free space. Several methods have been developed to

supplement the THz generation capabilties, yielding single-cycle pulses with 50 J energy,

frequency-tunable multicycle pulses with 10 J energy, and field enhancement of multicycle

pulses with 0.5 MV/cm peak-to-peak fields and very high spectral brightness [2].

The THz generation methodology came about through time-resolved vibrational

spectroscopy of soft modes in ferroelectric phase transitions, and these modes remain

subjects of intensive effort in which intense THz pulses are used as the driving fields. More

generally, strong THz fields have generated nonlinear electronic, vibrational, and rotational

responses, and nonlinear THz spectroscopy experiments including time-resolved THz-

pump/THz-probe measurements have been conducted on solid, liquid, and gas-phase samples

[3-6]. Recent progress and prospects for coherent control [7] will be reviewed.

References:

[1] K.-L. Yeh, M.C. Hoffmann, J. Hebling, and K.A. Nelson, Appl. Phys. Lett. 90 (2007)

171121.

[2] Z. Chen, X. Zhou, and K.A. Nelson, submitted; C.A. Werley et al., submitted.

[3] J. Hebling et al, IEEE J. Sel. Topics Quant. Electron. 14 (2008) 345.

[4] M.C. Hoffmann et al., Physical Review B 79 (2009) 161201 (R); Appl. Phys. Lett. 95

(2009) 231105.

[5] H.Y. Hwang et al., arXiv:1101.4985v1 {cond-mat.mtrl.-sci] 26 Jan 2011; submitted.

[6] S. Fleischer, Y. Zhou, R.W. Field, and K.A. Nelson, submitted.

[7] T. Qi, Y.-H. Shin, K.-L. Yeh, K.A. Nelson, and A.M. Rappe, Phys. Rev. Lett. 102 (2009)

247603.

Talks Friday

Terahertz dynamics of water in eutectic LiCl solution: bulk water and

worm-hole structures

David A. Turton,a,b C. Corsaro,c M. Candelaresi,a A. Brownlie,d K.R. Seddon,d F.

Mallamace,c,e and Klaas Wynnea,b*

a School of Chemistry, Univ. Glasgow, UK. b Dept. of Physics, Univ. Strathclyde, Glasgow,

UK. c Dipartimento di Fisica, Univ. di Messina, Italy. d School of Chemistry, Queen's Univ.

Belfast, UK. e Dept. of Nuclear Science and Engineering, MIT, Cambridge, USA.

The behaviour of liquid water below its melting point is of great interest as it may hold clues

to the properties of normal liquid water and of water in and on the surfaces of biomolecules.

A second critical point, giving rise to a polyamorphic transition between high and low density

water, may be hidden in the supercooled region but cannot be observed directly. Here it is

shown that water can be locked up in nano-pools or worm-like structures using aqueous LiCl

salt solutions and maintains its bulk-like properties.

Very high dynamic range ultrafast femtosecond

optical Kerr effect (OKE) spectroscopy is used to

study the temperature-dependent behaviour of

water in these nano-pools on timescales from 10 fs

to 4 ns. These experiments are complemented by

temperature-dependent nuclear magnetic resonance

(NMR) diffusion measurements, concentration-

dependent Fourier-transform infrared (FTIR)

measurements, and temperature-dependent

rheology. It is found that liquid water in the

nanoscale pools undergoes a fragile-to-strong transition at about 220 K associated with a

sharp increase in the inhomogeneity of translational dynamics. OKE measurements in the

glass confirm the complex nature of the hydrogen-bonding modes reported for neat room-

temperature water and support predictions of anomalous diffusion due to ‘worm-hole’

structure.

References:

[1] D.A. Turton, M. Candelaresi, D.F. Martin, and K. Wynne, Nature Chemistry, under

review (2011).

[2] D.A. Turton, C. Corsaro, M. Candelaresi, A. Brownlie, K.R. Seddon, F.Mallamace, and K.

Wynne, Faraday Disc. in press (2011)

6

5

4

3

2

1

0

SO

KE /

arb

.un

its

2 4 6 810

2 4 6 8100

2 4

Wavenumber /cm-1

CI LATA

CI TA LA

130 K

298 K

H2O

LiCl/H2O6.7 M

Figure 1 OKE spectra (log frequency scale) of neat

water (black) and a eutectic solution of LiCl in water

at room temperature (green) and in the glass

H-bond structures and structural relaxation in aqueous solutions of

electrolytes

Ismael A. Heisler, Kamila Mazur and Stephen R. Meech

School of Chemistry, University of East Anglia, Norwich NR4 7TJ, UK

The solvation of ions in aqueous solutions is critical to the stability and structure of

numerous chemical and biological species. Further, the dynamics of water molecules in the

solvation shell play an important role in determining the rate of structural transformations, for

example in protein folding, ligand binding, etc. In this paper the solvation structure and the

dynamics of solvation water will be probed using the time domain diffractive-optic transient-

grating optical Kerr effect.1,2 This geometry permits the direct determination of the

anisotropic and isotropic polarisability relaxation, equivalent to a high signal-to-noise Raman

spectral density in the THz frequency range. This measurement yields information on the

symmetry of vibrational modes, the H-bond structure and the relaxation dynamics in aqueous

solutions.3

The isotropic response of aqueous NaCl yields a vibrational mode which is absent in the

pure water response.4 This can be assigned to a totally symmetric mode of the hydrogen

bonded structure of the halide ion, permitting an estimation of the bond force constant, which

is similar to that of the water – water H-bond. The concentration dependence of the mode

suggests an effect of cation charge on the frequency of the halide water bond. These isotropic

data are contrasted with measurements of the anisotropic response, which probes the solution

H-bond structure and its picosecond relaxation dynamics, both of which are concentration

dependent. These measurements have been extended to study the hydroxyl ion, where the H-

bond is stronger than for the halide water case and more highly polarized.

References:

[1] G. D. Goodno, G. Dadusc and R. J. D. Miller. J. Opt. Soc. Am. B 15 (1998) 1791.

[2] I. A. Heisler and S. R Meech J. Phys. Chem. B 112 (2008) 12976.

[3] C. J. Fecko, J. D. Eaves and A. Tokmakoff J. Chem. Phys. 117 (2002) 1139.

[4] I. A. Heisler and S. R Meech, Science 327 (2010) 857.

Ultrafast dynamics of photolyzed carbon monoxide in the primary docking

site of heme domain variants of the oxygen sensor FixL

Patrick Nuernberger, Kevin F. Lee, Adeline Bonvalet, Latifa Bouzhir-Sima, Ursula Liebl,

Manuel Joffre, and Marten H. Vos

Laboratoire d'Optique et Biosciences, Ecole Polytechnique, CNRS UMR 7645, INSERM

U696, 91128 Palaiseau, France, marten.vos@polytechnique.edu

In heme-based sensor proteins ligand binding/dissociation from heme in a sensor domain

induces directed conformational changes leading eventually to changes in the enzymatic

activity of an associated catalytic domain. The bacterial oxygen sensor FixL is the best

studied example of these proteins and displays marked differences in dynamic behavior upon

ligand dissociation with respect to model globin proteins1. We report a mid-IR study of the

ultrafast dynamics of CO in the docking site of wild type and R220H (somewhat ‘myoglobin-

like’) mutant FixLH. We employ a recently developed chirped-pulse upconversion method2

that allows for simultaneous measurement

of the absorption of both heme-bound and

docked CO with very high spectral

resolution (~2 cm-1) and sensitivity.

Remarkable results complementing earlier

studies3 include the observation of higher

vibrational levels of CO (see Figure) and

orders of magnitude faster vibrational

relaxation in FixL than in globins, as well

as novel CO orientation properties.

References:

[1] Kruglik, S.G., Jasaitis, A., Hola, K., Yamashita, T., Liebl, U., Martin, J.-L., Vos, M.H. Proc. Natl. Acad. Sci. U.S.A. 104 (2007) 7408. [2] Nuernberger, P., Lee, K.F., Bonvalet, A., Vos, M.H., Joffre, M., J. Phys. Chem. Lett. 1 (2010) 2077. [3] van Wilderen, L.J.G.W., Key, J.M., Van Stokkum, I.H.M., van Grondelle, R., Groot, M.L., J. Phys. Chem. B 113 (2009) 3292.

Tetracycline structure and dynamics in methyl sulfoxide

Victor Volkov1, Roberto Righini1,2

1 European Laboratory for Nonlinear Spectroscopy (LENS), I-50019 Sesto Fiorentino, Italy 2 Department of Chemistry, University of Florence, I-50019 Sesto Fiorentino, Italy

Tetracyclines comprise a large number of antibiotics that contain an octahydrotetracene-2-carboxamide skeleton of four linearly annealed six-member rings with a characteristic arrangement of double bonds and hydroxyls. Theoretical studies indicated that tetracycline is a very adaptive molecule, capable of easily modifying itself through tautomerism in response to various chemical environments. In this study we show that quantum calculations and linear and non-linear infrared experiments converge to the identification of the predominant form of neutral tetracycline out of 11 possible tautomers in DMSO.

The different arrangements of the main structural moieties in the selected tautomers suggest that their infrared response can be specific enough to help in the experimental identification. We explore comparatively the spectral signatures of tetracycline in DMSO detected in FTIR and nonlinear infrared time-resolved spectra, in comparison with the spectral features of 11 possible tautomers as predicted by quantum calculations. The calculated energies and vibrational spectra allow us to restrict our search to two tautomers only. The complex cross-peak pattern that appears in the 1420-1620 cm-1 region of the 2D-IR spectrum is of help in solving the ambiguity. In particular, the relatively weak coupling observed when pumping at 1660 cm-1 (the COH bending on the right side terminal ring) and probing in the 1520-1620 cm-1 region, is consistent with the calculated non-linear response of tautomer 2 rather than 4.

The large inhomogeneous component of the band at 1660 cm-1 and its time evolution are discussed in terms of the intramolecular hydrogen-bond dynamics, in comparison with the results of quantum calculations.

1500 16001500 1600 1500 1600

1500

1600

1500 1600

Pu

mp

Fre

qu

en

cy

(cm

-1)

Str, 4

1500 1600

Exp..

1500 1600

1500

1600

Probe Frequency (cm-1)

Str. 2

1500 1600

1500 1600

Theory: str. 4

Theory: str. 2

Experiment

Learning about Intermolecular Interactions from Spectroscopic Probes in

Proteins and Solution

Myung Won Lee1, Pierre Andre Cazade1, Stephan Lutz1, and Markus Meuwly1

1 Department of Chemistry, University of Basel, Basel, Switzerland, m.meuwly@unibas.ch

Vibrational spectroscopy is exquisitely sensitive to intermolecular interactions. This opens to

the possibility to utilize computer experiments to learn about how molecules interact with

each other from comparing experimental observables with computations. Infrared (IR)

spectroscopy has served as a useful tool to characterize protein and ligand dynamics.[1-3]

Contrary to electronic spectroscopy, vibrational spectra contain signatures related to

geometrical structures. These changes can be directly associated with particular chemical

bonding patterns and are therefore more readily interpreted in terms of chemical structure.

Thus, an important goal of IR studies of proteins is concerned with the structural

interpretation of such spectra. This is, however, a difficult undertaking in most situations

because structure and spectroscopy can only be recorded at the same time under special

circumstances for protein-ligand systems. We will show how computer simulations with

accurate interaction potentials provide a structural understanding of vibrational signatures.[4-

7] A related problem but with different physical origin is the transfer of vibrational energy

from a spectroscopic probe to the surrounding solvent. Although relaxation times can be

rationalized and analyzed from experiments with isotopically substituted solute and solvent

molecules, the interpretation in terms of energy relaxation pathways is generally difficult and

ambiguous. For the example of CN- in H2O and D2O[8-10] we show that accurate interaction

potentials explicitly demonstrate that relaxtion of one vibrational quantum of CN- proceeds

via coupling to librational and bending modes in the solvent.[11]

References:

[1] A. Ansari, et al., Biophys. Chem., 26 (1987) 337 –355. [2] P. A. Anfinrud, C. Han and R. M. Hochstrasser, PNAS 86 (1989) 8387 – 8391. [3] J. B. Johnson, et al., Biophys. J., 71 (1996) 1563 – 1573. [4] D. R. Nutt and M. Meuwly, PNAS 101 (2004) 5998 – 6002. [5] N. Plattner and M. Meuwly, Biophys. J., 94 (2008) 2505 – 2515. [6] S. Lutz, K. Nienhaus, G. U. Nienhaus and M. Meuwly, J. Phys. Chem. B 113 (2009) 15334. [7] S. Lutz and M. Meuwly, Faraday Disc. (2011) in print. [8] Heilweil, E. J.; Doany, F. E.; Moore, R.; Hochstrasser, R. M. J. Chem. Phys. 76 (1982) 5632–5634. [9] Hamm, P.; Lim, M.; Hochstrasser, R. M. J. Chem. Phys. 107 (1997) 10523–10531. [10] Rey, R.; Hynes, J. T. J. Chem. Phys. 108 (1998) 142–153. [11] M. W. Lee and M. Meuwly, J. Phys. Chem. A. (2011) in print.

Ground- and Excited State Vibrational Coherence Dynamics in all-trans

Retinal Protonated Schiff-Bases investigated with (Pump) DFWM

J.P. Kraack1, T. Buckup1, and M. Motzkus*1

1Physikalisch-Chemisches Institut, Ruprecht-Karls Universität Heidelberg, D-69210

Heidelberg, Germany, *E-Mail: marcus.motzkus@pci.uni-heidelberg.de

Time-resolved Degenerate Four-Wave-Mixing (DFWM) and Pump-DFWM are

advantageous multi-dimensional non-linear spectroscopic methods for investigations of

vibrational coherence dynamics [1]. Here, we apply both methods with sub-20 fs pulses for

investigations on vibrational coherence dynamics in ground and excited electronic states of

all-trans retinal protonated Schiff bases (RPSB). We characterize the time evolution of high-

frequency (HF, > 800 cm-1) and low-frequency (LF, < 800 cm-1) coherence signal

modulations in detail and assign them to underlying potential energy surfaces. Ground-state

LF coherences appear strongly overdamped, contrasting to coherence dynamics in the excited

state which consist exclusively of intense LF modulation [2]. Moreover, Pump DFWM

reveals that LF modes can only be induced in a narrow time window after initial excitation

(Fig. 1). We demonstrate that LF modes are activated via internal vibrational energy

redistribution, supporting previous results [3]. However, in contrast to earlier reports [2, 3],

such LF modes are observed already for excitation on the red edge of ground state absorption.

Our results thus allow an extension of the current view of RPSB’s photo-isomerization.

Fig. 1. (a) Pump-DFWM scan of RPSB at 640nm. (b) DFWM-dynamics initiated by pu/St-pulses are depicted vs. T.

References:

[1] T. Hornung et al., Chem. Phys. Lett. 402 (2005) 283.

[2] B. Hou et al., J. Phys. Chem. A 105 (2001) 7042.

[3] G. Zgrablic et al., Chem. Phys. 338 (2007) 168.

Tracking the Pathway of an Ultrafast Photoinduced Bimolecular Charge

Separation Reaction

K. Adamczyk2, J. Dreyer2, M. Koch1, B. Lang1, E. Nibbering2and E. Vauthey1

1 Dep. of Physical Chemistry, University of Geneva, Switzerland, bernhard.lang@unige.ch

2 Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Berlin, Germany

Photo-induced electron transfer (ET) between donor-acceptor (DA) pairs, often considered

as the simplest of chemical reactions, plays an important role in many areas of chemistry and

biology. In general, the classical Marcus theory is applied to rationalize the kinetics of ET

reactions, though the predicted inverted region has never been observed experimentally for

bimolecular photo induced ET [1,2]. The formation of ions in an electronically excited state

has been invoked to account for this fact. However, a direct spectroscopic verification has not

been possible yet as the excited electronic states of radical ions are in general very short lived.

The figure shows the hot ground state spectral signature (HGS) of the antisymmetric CN

stretch vibration of tetracyanoethylene upon ultrafast ET with perylene and subsequent charge

recombination. A simulation of the band shape as a function of temperature allows to estimate

the amount of energy released to the reaction partners. Considering the amount of energy

released in the subsequent steps, the corresponding reaction channel can be assigned. A

comparison of the HGS between DA pairs where an electronic excited state of one of the ions

is accessible and pairs where these states are situated too high in energy is fully consistent

with the formation of ions in electronically excited states where this is energetically possible.

References:

[1] D. Rehm and A. Weller, Isr. J. Chem. 8 (1970) 259.

[2] E. Vauthey, J. Photochem. Photobiol. A 179 (2006) 1.

Poster Abstracts

The Role of Protein–Ligand Interactions in Ligand Binding and

Equilibrium Structural Fluctuations of Myoglobin

Katrin Adamczyk a, Marco Candelaresi a, Kirsty Robb b, Rafal Kania a, Spyridon Kaziannis a,

Michael Towrie c, Gregory M. Greetham c, Anthony W. Parker c, Nicholas P. Tucker b, and

Neil T. Hunt a

a E-mail: katrin.adamczyk@strath.ac.uk, Dept. of Physics, University of Strathclyde,

Glasgow, UK b Strathclyde Institute for Pharmacy and Biomedical Sciences, University of

Strathclyde Glasgow, UK c Central Laser Facility, STFC Rutherford Appleton Laboratory,

Didcot, Oxon, UK

How does the mutation of the Myoglobin (Mb) haem pocket alter the equilibrium protein

dynamics and ligand binding? To address this question, we have studied wild type and H64Q

mutant forms of nitrosylated Mb. In the Mb mutant, the distal His64 residue is replaced with

Glu. The equilibrium protein dynamics for the wild type Mb and the two distinct substates of

the Mb mutant are examined using Fourier transform two-dimensional infrared (FT2D-IR)

spectroscopy. The time dependent changes in the 2DIR line shapes for both proteins are

analysed to obtain the frequency-frequency correlation function. The results for the Mb

mutant are compared to the wild type Mb. Using UVpump-IRprobe spectroscopy, photo-initiated

rebinding kinetics of H64Q-NO and Mb-NO are studied in order to explore the effect of the

protein-ligand interactions on the rebinding characteristics. This data extends recent studies of

ferric haem nitrosyls that indicated a direct link between ultrafast equilibrium fluctuations and

ligand rebinding dynamics[1].

:

Fig 1: 2D-IR spectra of NO bound to mutant Mb H64Q (A) and wild type Mb (B) at waiting time T =

3.5ps showing elongated bands along the diagonal.

[1] Neil T. Hunt et al., Biochem. J. 433, 459 (2011).

Poster 1

Temperature dependence of vibrational relaxation of the OH bending

excitation in liquid H2O

Satoshi Ashihara1 and Sachi Fujioka1

1 Dept. of Applied Physics, Tokyo Univ. of Agriculture and Technology,

2-24-16 Nakacho, Koganei, Tokyo 184-8588 Japan

ashihara@cc.tuat.ac.jp

The population relaxation, resonant energy transfer, and spectral diffusion of the OH

stretching vibration in liquid water have been intensively studied. Compared with the OH

stretching vibration, much less is known about the dynamics of the OH bending vibration.1,2

This mode has the lowest frequency among the intramolecular modes and therefore its energy

relaxation process should be a sensitive probe of the intermolecular interactions. Rey et al.3

reported the relaxation dynamics the bending vibration by the classical MD simulations.

We have studied the temperature dependence of the population relaxation of the OH

bending excitation in pure H2O by use of the mid-infrared pump-probe spectroscopy.4 The

vibrational relaxation of the OH bend excitation exhibited anomalous temperature

dependence, similar to the OH stretching excitation.5,6 Above room temperature, the

population lifetime monotonically increased from 170 ± 15 fs at T = 295 K to 250 ± 15 fs at T

= 348 K. This temperature dependence can be explained by the decrease in the spectral

overlap between the OH bending vibration and the librational modes at higher frequencies. In

this regard, our results support the relaxation scenario that the bend vibrational energy is

dominantly transferred to high-frequency librations. The relaxation rate becomes almost

temperature independent below room temperature within the liquid phase, the possible origin

for which will be discussed. References:

[1] S. Ashihara, N. Huse, A. Espagne, E. T. J. Nibbering, T. Elsaesser, Chem. Phys. Lett. 424

(2006) 66.

[2] J. Linder, P. Voehringer, M. S. Pshenichnikov, D. Cringus, D. A. Wiersma, M. Mostovoy,

Chem. Phys. Lett. 421 (2006) 329-333.

[3] R. Rey, F. Ingrosso, T. Elsaesser, J. T. Hynes, J. Phys. Chem. A 113 (2009) 8949.

[4] S. Ashihara, S. Fujioka, K. Shibuya, Chem. Phys. Lett. 502 (2011) 57.

[5] A. J. Lock, H. J. Bakker, J. Chem. Phys. 117 (2002) 1708.

[6] D. Kraemer, M. L. Cowan, A. Paarmann, N. Huse, E. T. J. Nibbering, T. Elsaesser, R. J.

D. Miller, Proc. Nat. Acad. Sci. 105 (2008) 437.

Poster 2

Ultrafast vibrational probing of heat transport through model membrane

systems

Ellen H. G. Backus1, Johanna M. Kuiper2, Jan B. F. N. Engberts2, Bert Poolman2,

Mischa Bonn1 and Huib J. Bakker1

1 FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands

2 University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands

About 50% of the proteins in the human body are embedded in, or present at cell

membranes. These proteins are generally actively driven, and therefore locally produce heat

while functioning. To avoid local overheating this heat has to be transported away very

efficiently. Here, we aim to unravel the mechanism of this heat transport through the

membrane. To that purpose, a model membrane system (see Fig. 1) was studied consisting of

hydrated multiple bilayers of a conventional lipid (for example DPPC) mixed with a lipid

having an azobenzene group in its tail (i.e. a photoswitchable lipid). After excitation with a

100 fs pulse at 430 nm, azobenzene undergoes cis-trans isomerisation resulting in a large and

rapid local heating. The subsequent picosecond heat transport is monitored by local molecular

thermometers provided by molecular vibrations, through the time-dependent frequency shifts

of the C=C vibration of the azobenzene (the source), the C=O vibration in the head group of

the DPPC molecules (see Fig. 1), and the vibrations of water around the lipids. By positioning

the azobenzene group at different positions within the photo-lipid (i.e. close to or far from the

head group), we study the distance dependence of the rate and mechanism of heat transfer. Figure 1: left: sketch of the model membrane system consisting of DPPC and lipids with an azobenzene group in their tail; right: time-dependent absorbance changes of the C=C and C=O vibration after exciting the azobenzene

chromophore of the lipid with 430 nm illustrating the heat flow from the azobenzene group to the head group of the lipid DPPC.

Poster 3

-2.0

-1.0

0.0

-0.8

-0.4

0.0

0.4

100806040200

abso

rban

ce c

hang

e (m

OD

)

time (ps)

C=C vibration from azobenzene

C=O vibration from DPPC

-2.0

-1.0

0.0

-0.8

-0.4

0.0

0.4

100806040200

abso

rban

ce c

hang

e (m

OD

)

time (ps)

C=C vibration from azobenzene

C=O vibration from DPPC

Selective Response Preparation and Interference Phenomena in ultrafast

spectrally resolved Degenerate Four-Wave-Mixing

J.P. Kraack1, M. Motzkus1, and T. Buckup*1

1Physikalisch-Chemisches Institut, Ruprecht-Karls Universität Heidelberg, D-69210

Heidelberg, Germany,* E-Mail: tiago.buckup@pci.uni-heidelberg.de

Spectrally resolved, homodyne detected Degenerate Four-Wave-Mixing is a powerful

method in the investigation of molecules in the gas-phase [1] as well as in the condensed-

phase [2]. In spite of its success, the homodyne detection results in interferences between

different response pathways. These can have dramatic influence on the signal dynamics and

its interpretation. Such phenomena include the appearance of combination frequencies from

normal modes, complex time-evolution of signal oscillations as well as destructive

interference of signal contributions. In this context, we exploit specific dependences of the

signal dynamics on relative pulse delays as well as on phase-modulation (chirp) of the

excitation and probing pulses in DFWM in order to disentangle interference contributions and

molecular wave packet dynamics. Specifically, an easy experimental method, that allows

selective preparation of ground state nonlinear response pathways, is demonstrated and its

application is discussed in detail. The experimental results are additionally compared to

numerical calculations which provide an in-depth understanding of underlying processes.

Fig. 1. Selective preparation of ground state response pathways (R3 and R4) using chirped excitation pulses.

References:

[1] I. Pastirk et al., JPCA 103 (1999) 10226.

[2] T. Hornung et al., Chem. Phys. Lett. 402 (2005) 283.

Poster 4

Investigation of the Dynamics of Nitrosylated Corynebacterium glutamicum

Catalase Protein by Fourier transform-2D-IR Spectroscopy

Marco Candalaresi a, Katrin Adamczyka,Rafal Kania,a Spyridon Kaziannis,aMichael Towrie,b

Gregory M. Greetham,b Anthony W. Parker,b Martin A. Walsh,c Nicholas Tuckerd and

Neil T. Hunta

a E-mail: marco.candelaresi@strath.ac.uk, Dept. of Physics, University of Strathclyde,

Glasgow, UK; b Central Laser Facility, STFC Rutherford Appleton Laboratory, UK; cDiamond Light Source Ltd, Didcot, Oxon, UK; dStrathclyde Institute for Pharmaceutical

and Biomedical Sciences, University of Strathclyde, Glasgow, UK.

The structure and dynamics of the NO binding site of the Corynebacterium glutamicum

catalase protein have been investigated by Fourier transform two-dimensional infrared

(FT2D-IR) spectroscopy, time-resolved UVpump-IRprobe infrared spectroscopy (TRIR) and X-

ray crystallography. 2D-IR spectra show spectral diffusion due to fluctuations of the haem

pocket of catalase leading to a frequency-frequency correlation function with a decay

timescale of ~5 ps while TRIR data reveal the NO ligand rebinding dynamics following

photoloysis. Comparison of these timescales in catalase with other haem-containing proteins,

including cytochrome c, provides further evidence regarding links between the flexibility of

the haem pocket and ligand binding dynamics of NO sensing proteins.1

Fig.1: FT2D-IR spectra obtained for, left, catalase protein and, centre, equine heart

cytochrome c with a waiting time of 4.5 ps. Right, X-ray diffraction pattern of catalase

crystal.

[1] N. T. Hunt, G.M. Greetham, M.Towrie, A.W. Parker, N.P. Tucker. Biochem. J. 433

(2011) 459.

Poster 5

Ultrafast vibrational dynamics in free polyatomic molecules excited by IR

femtosecond radiation

S.V. Chekalin, V.O. Kompanets, V.B. Laptev, A.A. Makarov, S.V. Pigulsky, and

E.A. Ryabov

Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow Region, Russia

142190, E-mail: chekalin@isan.troitsk.ru

Vibrational dynamics in (CF3)2CCO, (CF3)2CO, C4F9COI, HCOOC2H5, CH3COOC2H5, and

CH2CHCOOC2H5 molecules induced by multiphoton resonant excitation of CCO and CO

vibrations by mid-infrared ( ~ 5μ) femtosecond laser pulses was studied. The IR pump-probe

technique with spectral analysis of probe radiation was used. All measurements were

performed in a gas phase to avoid any influence of intermolecular interactions. The duration

of both pump and probe pulses inside the gas cell was about 300 fs with a spectral width ~

230 cm-1. The amplitude and spectral changes of the induced variation of optical density ΔOD

were measured as a function of pump-probe delay time.

Exponential decay of the ΔOD signal in the pumped resonant modes was observed for all

molecules studied. The characteristic decay time values were measured and found to be varied

from 2.6 ps (C4F9COI) to 18 ps (HCOOC2H5). We attributed this decay to vibrational energy

transfer from the excited mode to the other modes of molecules (intramolecular vibrational

redistribution - IVR).

The spectral measurements proved that IR multiphoton excitation of the resonant vibrations in

the molecules under study takes place. The mode-selective population of the resonant modes

with v = 6 (CCO ν1 mode) was detected in (CF3)2CCO molecules. The IVR rates for different

states of the pumped ν1 mode of (CF3)2CCO molecule were measured.

For the first time, the “two color” experiments with pumping of ν1 =2194 cm-1 mode and

probing of other more low-frequency modes were carried out with (CF3)2CCO molecule.

Bleaching of v=0 v=1 transition and absorption increase for higher-lying transitions of

these nonresonant modes was observed. The kinetic curves were found to be distinct for

different modes. This give valuable information about the pathways of IVR process from the

pumped mode to the other molecular modes.

Acknowledgments: This work was supported in part by Russian Foundation for Basic

Research.

Poster 6

Vibrational relaxation of small molecules isolated in low-temperature

matrices.

Wutharath Chin1, Raphaël Thon1, Jean-Pierre Galaup2, and Claudine Crépin1

1 Institut des Sciences Moléculaires d'Orsay, CNRS - Université Paris Sud, Orsay (France),

wutharath.chin@u-psud.fr

2 Laboratoire Aimé Cotton, CNRS - Université Paris Sud, Orsay (France)

The vibrational coherence of an oscillator informs on the dynamical processes due to

environment effects, that can be due to the surrounding medium (the liquid or in our case, the

cryogenic matrix) or/and to the other oscillators of the system through intramolecular

interactions for instance. To date few experimental works have reported on the vibrational

relaxation in low-temperature matrices and most studies were dedicated to systems in liquids

[1]. Few years ago, our group measured the dephasing and the population relaxation times in

matrices by photon echo technique [2].

We aim at investigating larger organic molecules, which requires using

ultra-short (subpicosecond) laser pulses. Following our previous studies,

we here present preliminary results on the vibrational dynamics of

W(CO)6 in CCl4 and isolated in N2 matrix investigated at the

femtosecond timescale. Our IR absorption studies on glycolaldehyde

molecule (see figure) in solid parahydrogen showed inhomogeneous

contributions to the spectrum [3]. Time-resolved experiments are thus

currently in progress to determine the influence of the environment on the vibrational

dynamics (ex: nature of the matrix and H-bonding).

References:

[1] M. D. Fayer, Ann. Rev. Phys. Chem. 60 (2009) 21 and refs therein.

[2] M. Broquier, C. Crépin, H. Dubost, and J.-P. Galaup, Chem. Phys. 341 (2007) 207, M.

Broquier, C. Crépin, A. Cuisset, H. Dubost, and J.-P. Galaup, Eur. Phys. J. D 36 (2005) 41.

[3] J. Ceponkus, W. Chin, M. Chevalier, A. Limongi, M. Broquier, and C. Crépin, J. Chem.

Phys. 133 (2010) 094502.

Poster 7

Cc conformer of Glycolaldehyde

Vibrational Dynamics of [Lu(Pc)2]-1 Probed with Broadband Pump-Probe

and Two-dimensional Electronic Spectroscopy

Niklas Christensson1, Igor Pugliesi2, Maximilian Bradler2, Franz Milota1, Oliver Bixner1,

Eberhard Riedle2, Harald F. Kauffmann1, Jürgen Hauer1

1 Faculty of Physics, University of Vienna, Strudlhofgasse 4, 1090 Vienna, Austria 2Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians-University, Oettingerstr. 67,

80538 Munich, Germany

Ultra-broadband pump-probe and two-dimensional electronic spectroscopy (2D-ES) have

been used to probe the vibrational dynamics in a lutetium bisphthalocyanine [Lu(Pc)2]- dimer.

Figure 1 (a) shows the pump-probe signal at 500 fs and the insert displays the transients at

22200, 15600 and 14900 cm-1, showing a 160 cm-1 mode with 1 ps decay time. The

modulation at 15600 and 14900 cm-1 shows an anti-correlated spectral motion, which was

assigned in a previous study to a ground state wave-packet and transitions to two oppositely

displaced PES1. However, the observation of the same frequency and damping time in ESA

suggest that such modulations could result from an ESA transition involving an excited state

wave-packet and the doubly excited state of the dimer (overlapping with GSB). Because these

models cannot be distinguished in pump-probe, we turned to 2D-ES. Figure 1 (b) shows the

2D spectrum at t2=150 fs, while figure 1 (c) shows the kinetics of the different peaks overlaid

with the oscillations from pump-probe. The (negative) ESA peak displays a clear modulation,

while the upper diagonal peak (cp4) only shows decay. This shows that the anti-correlated

spectral motion can be understood via an excited state wave-packet and a first and second

excited state displaced in opposite directions.

Figure 1. (a) Pump-Probe signal at t2=500 fs. The insert displays kinetics (from bottom)

at 22200, 15600 and 14900 cm-1. (b) 2D spectrum at t2=150 fs. Positive (negative)

features are drawn in 5% steps as thick (dashed) lines (c) Kinetics of the peaks in (b). 1 Prall B.S., Parkinson D.Y., Ishikawa N., and Fleming G.R., JPCA, 109: 10870 (2004).

Poster 8

Characterization of Laser Emission at High Spectral Resolution on a

Nanosecond Timescale

Chris Colley1, John Wilson2, Frank Weston3 1 Agilent Technologies, Melbourne, Victoria, Australia. chris.colley@agilent.com

2 Agilent Technologies, Yarnton, Oxfordshire, UK. john.wilson@agilent.com 3 Agilent Technologies, Wilmington, Delaware, USA. frank.weston@agilent.com

Step-scan time resolved FTIR spectroscopy provides a unique approach for monitoring

short term transient events such as laser excitation of chemical reactions or electrochemical

events.

In step scan mode, time based data are collected at discrete optical retardations. At each

optical retardation the spectrometer will wait to receive a trigger signal from an external

device such as a laser to begin collection (slave mode) or alternatively the spectrometer will

send a trigger signal to an external device to begin a process (master mode).

The experiment described will look at high resolution (0.07 cm-1) measurements on a

nanosecond timescale. At low spectral resolution, 8cm-1, the emission from a pulsed laser

diode can be observed at ca. 6400 cm-1 with a 200 ns pulse length and an apparent rise-time

of 40 ns. If the laser emission is measured with higher spectral resolution, 0.07 cm-1, the

emission can be resolved into a number of discrete laser modes each with differing dynamic

profiles.

Poster 9

Light-triggered aggregation and disassembly dynamics of

amyloid-like structures from picoseconds to minutes.

Andreas A. Deeg, Wolfgang Zinth

BioMolecular Optics, Faculty of Physics, Ludwig-Maximilians-University Munich,

Andreas.Deeg@physik.uni-muenchen.de

The aggregation of peptides into amyloid structures is associated to a variety of diseases

such as Creutzfeld Jacob and Alzheimer. On the other hand the unique material properties of

amyloids make them interesting candidates for the production of nano-biomaterials. The

model peptide used in this study contains two amino acid strands connected by an azobenzene

which serves as a light trigger. A similar compound was used recently for the investigation of

ultrafast dynamics of -Hairpin formation [1, 2]. Investigations with Transmission Electron

Microscopy, Small Angle Neutron Scattering and mid IR spectroscopy revealed that the

peptide forms amyloid-like aggregates when the azobenzene is in the trans conformation.

Illumination of the aggregated sample which switches the azobenzene to the cis form initiates

disaggregation [3]. The dynamics of light triggered disaggregation were studied on different

timescales by time resolved vibrational spectroscopy. Excitation of the azobenzene switch

leads to characteristic changes of the IR-spectrum of the aggregate on the ps and ns timescale.

They can be related with population of the excited electronic state of the azobenzene, with

isomerization (which takes place in less than 10 ps) and subsequent relaxation of the structure

of the model peptide (ps to ns time scale). However, the final disassembly of the amyloid-like

structures was found to take place on the timescale of minutes.

References:

[1] S.L. Dong, M. Löweneck, T. E. Schrader, W. J. Schreier, W. Zinth, L. Moroder, C.

Renner, Chem. Eur. J. 12 (2006) 1114

[2] T. E. Schrader, W. J. Schreier, T. Cordes, F. O. Koller, G. Babitzki, R. Denschlag, C.

Renner, M. Löweneck, S.-L. Dong, L. Moroder, P. Tavan, W. Zinth, Proc. Natl. Acad. Sci.

USA 104 (2007) 15729

[3] A. A. Deeg, T. E. Schrader, S. Kempter, J. Pfizer, L. Moroder, W. Zinth, ChemPhysChem

12 (2011) 559

Poster 10

Modeling amide I and II modes in polypeptides

Arend G. Dijkstra12, Thomas la Cour Jansen2 and Jasper Knoester2

1 Department of Chemistry, Graduate School of Science, Kyoto University,

dijkstra@kuchem.kyoto-u.ac.jp

2 Institute for Theoretical Physics and Zernike Institute for Advanced Materials

We model the properties of amide I and II modes in polypeptides and calculate vibrational

energy dynamics and nonlinear infrared spectra. Although the amide I mode is the most

studied vibration in the peptide backbone, it is not completely independent of other modes, in

particular, the amide II. We therefore introduce a description that treats both vibrations on an

equal footing, and includes coherent couplings between them. Using molecular dynamics

simulations, we furthermore investigate the partially correlated effect of low-frequency

dynamics in the solvent on the observed amide modes. We apply the model to study the

partially coherent transport of vibrational energy through a model alpha-helix. Coherences in

the helix are found to survive for 0.5-1 ps, leading to coherent transport on a similar time

scale. This transport, as well as the energy relaxation between amide I and II modes, is

reflected in the calculated two-dimensional infrared spectra.

References:

[1] A.G. Dijkstra, T.l.C. Jansen and J. Knoester, J. Phys. Chem. A 114 (2010) 7315

[2] A.G. Dijkstra, T.l.C. Jansen and J. Knoester, J. Phys. Chem. B (2011) DOI: 10.1021/jp109431a

Poster 11

Time resolved infrared study of the recombination dynamics of the carbon

monoxide complex of Bacillus subtilis truncated hemoglobin.

Mariangela Di Donato, Andrea Lapini, Barbara Patrizi, Agnese Marcelli, Paolo Foggi and

Roberto Righini

LENS (European Laboratory for non linear Spectroscopy) via Nello Carrara 1, 50019 sesto

Fiorentino (FI), Italy. didonato@lens.unifi.it

Truncated hemoglobin from Bacillus subtilis is a small oxygen binding protein presenting an

extremely high oxygen affinity and a very slow oxygen release rate. Previous characterization

by resonance Raman and FTIR spectroscopy [1] evidenced the occurrence of specific

hydrogen bonding interactions between the amino acid residues located in the proximity of

the heme group and the coordinated ligand. In order to elucidate the structure-function

relationships determining the protein behavior with respect to the ligand dissociation

dynamics, we performed time resolved ultrafast visible-pump/Mid-infrared-probe

experiments, investigating the dynamics of carbon monoxide recombination upon

photodissociation by visible pulses at 400 nm. The analyzed spectral region, involving both

the bleached band of the heme-CO complex and the absorption band of the released CO,

allows to obtain structural information concerning the localization of the photodissociated

ligand inside the protein docking site. The collected kinetic traces evidenced a

multiexponential kinetic behavior, with picoseconds components which can be ascribed to

fast geminate recombination induced by the presence of the strong hydrogen bonding network

in the heme pocket.

References:

[1] A. Feis, et al., Biochemistry, 47, (2008), 902-910.

Poster 12

UV/visible pump, infrared probe experiments for challenging samples: transient gratings and heterodyne detection

Paul M Donaldson, Halina Strzalka and Peter Hamm

Physikalisch-Chemisches Institut, Universität Zürich,

Winterthurerstrasse 190, CH-8057 Zürich, Switzerland

Measuring transient infrared spectra from low concentration or low signal species such as

labelled proteins or the capping layers of metal nanoparticles presents a major challenge for

even the most sensitive UV/visible pump infrared probe experiments. It is however well

known through single colour pump-probe experiments in the visible1 and in the infrared2 that

measurements can be made significantly more sensitive by generating the third order signal in

the so-called boxcars/transient grating geometry and using heterodyne detection.

In this poster we describe, to our knowledge, the first realisation of a UV/visible transient

grating experiment with a heterodyne detected broadband-dispersed infrared probe. The

experiment gives more than an order of magnitude improvement in signal to noise compared

with the pump probe geometry and is robust, compact and simple to operate. We generate

stable phase-locked UV/visible pulse pairs with tuneable spatial separation using a simple

arrangement of passive reflective optics. Phase locked infrared pulses for probing and

heterodyne detection are generated using in-house laser-burned CaF2 transmission gratings

and the simultaneous measurement of two infrared grating signals on separate detector arrays

allows for a balanced detection scheme to be used. Lossless signal modulation is also

performed using a 2.5 kHz quartz wobbler3 instead of a chopper.

(1) Goodno, G. D.; Dadusc, G.; Miller, R. J. D. J. Opt. Soc. Am. B-Opt. Phys. 1998, 15,

1791.

(2) Hamm, P.; Zanni, M. Concepts and methods of 2D Infrared spectroscopy; Cambridge

University Press, 2011.

(3) Bloem, R.; Garrett-Roe, S.; Strzalka, H.; Hamm, P.; Donaldson, P. Opt. Express, 18,

27067.

Poster 13

Amplification of Linear Dichroism for Ultrasensitive Femtosecond IR

Spectroscopy.

Julien Réhault1, Jan Helbing2

1,2 Physikalisch-Chemisches Institut, Universität Zürich,

Winterthurerstrasse 190, 8057 Zürich, Switzerland

1 julien.rehault@pci.uzh.ch, 2 j.helbing@pci.uzh.ch

We demonstrate strong amplification of polarization-sensitive transient IR-signals using a

pseudo-null crossed polarizer technique already successively applied for nanosecond flash

photolosys in the visible by Che et al. [1]. We

adapted the technique to ultrafast pulsed laser

spectroscopy in the infrared using photoelastic

modulators, which allow us to measure

amplified pump-probe signals at kilohertz

repetition rates. The method is demonstrated

for a photoswitch of the N-alkylated Schiff

base family in order to show its potential of

strongly enhancing sensitivity and signal to

noise in ultrafast transient IR experiments, to

simplify spectra and to determine

intramolecular transition dipole orientations [2]. Extension of the same measurement principle

to other frequency domains as well as multidimensional spectroscopies are possible.

References:

[1] D. Che, D.B. Shapiro, R.M. Esquerra, and D. S. Kliger, Chem. Phys. Lett. 224 (1994), 145.

[2] Réhault J, Zanirato V, Olivucci M and Helbing J, J. Chem. Phys. 134 (2011) 124516-10.

Poster 14

1550 1560 1570 1580 1590 1600 1610 1620

-10

-8

-6

-4

-2

0

2

0 10 20 30 40 50 600

102030405060

7 5 4 3 2 1

s x

10

3

Frequency (cm-1)

1° 2° 3° 5° 45°

En

ha

nce

men

t

Cot

signal

S/N

(°)

Laser induced pH jumps: oNBA proton release and pH equilibration

Mateusz L. Donten, Joost VandeVondele, Peter Hamm

1 University of Zurich, Institute of Physical Chemistry, Winterthurerstrasse 190, Zurich e-mail: phamm@pci.uzh.ch

Introduction: Transient pump-probe IR spectroscopy (TR-IR) and ab initio molecular

dynamics were used to study the mechanism of the o-Nitrobenzaldehyde (oNBA)

photoreaction and the dynamics of the resulting pH-jumps.

Proton transfer kinetics is considered “fast”. Thought the reaction rate for such processes is

diffusion limited (1011 M-1 s-1) their actual time scales may stretch far into the microsecond

ranges. In modern experiments optically triggered rapid proton release, pH-jumps, are often

applied to study kinetics of pH dependent processes such as protein folding, proton transfers,

etc. Description of how free protons are delivered and distributed after pH jumps is critical to

avoid confusions between kinetics of the examined process and solution equilibration.

oNBA is a proton cage molecule commonly used to perform optically triggered pH-jumps.

Despite extensive studies of its photoreaction, many details including the actual time scale of

the proton release remained controversial.

Experiment: Spectroscopic data (TR-IR) and ab initio MD simulations shown that the

reaction follows a two step mechanism with a ketene intermediate from which the final

carboxyl product was formed directly on a picoseconds timescale. Finally the proton

dissociated with a time constant ~20ns[1]. Its further fate was investigated with acetate ions as

an IR proton sensor and the simplest model for other pH jump experiments. The aqueous

solution undergoing the pH jump revealed highly complex, kinetically controlled behavior[2].

Initially, acetate ions (pKa 4.8) were observed protonated in presence of OH- (pKa 15.7). This

indicates that transiently the predictive power of thermodynamic parameters (i.e. pKa, pKw)

was lost as the system was controlled by its kinetics. The equilibrium in which hydroxyl ions

were neutralized was reached later with diffusion limited times of up to 0.1ms. Formulated

conclusions show a substantial need of kinetic description of pH-jump experiments.

References:

1. M. L. Donten, P. Hamm, J, VandeVondele; J Phys Chem B. 115 (2011) 1075-83 2. Paper in preparation M. L. Donten, P. Hamm

Poster 15

Probing impulsive vibrational dynamics near conical intersections

Kelly A Fransted, Gregory S Engel

James Franck Institute, Department of Chemistry, University of Chicago

Conical intersections, defined as singularities that connect multiple product wells to

the excited state potential energy surfaces, are known to be an integral component of chemical

dynamics. They mediate photochemical reactions via a singularity that arises from the

coupling of nuclear modes to electronic modes which ultimately leads to an ultrafast,

radiationless transition to the ground state. The coupling between electronic and nuclear

modes means that conical intersections are inherently non-Born-Oppenheimer, and the

ultrafast dynamics rely on the nuclear motion generated from an electronic excitation. The

outcome of any chemical reaction involving a conical intersection depends critically upon the

ensemble of trajectories passing near the singularity. Since the coupling of electronic and

nuclear modes gives rise to the sloped surface, the initial time period following an electronic

excitation is crucial in determining this trajectory. Hence, the shape and motion of the

electronic wavepacket on the excited state surface in the initial time period after excitation

can inform about the shape of the excited state surface. The shape of the excited state surface

subsequently provides insight into the nuclear modes that are dictating the trajectory through

a conical intersection.

Here, we present two-dimensional (2D) electronic spectra of pinacyanol iodide

showing an excited state wavepacket coherently accelerating toward a conical intersection.

The data show an excited state wavepacket accelerating out of the Franck-Condon region and

shifting to lower energies on an ultrafast time scale. The wavepacket maintains a memory of

the static disorder in the system as it moves toward the intersection singularity, but no

bifurcation of the wavepacket is observed. We therefore conclude that the initial trajectory is

dominated by the slope of the upper state surface rather than by solvent fluctuations or initial

nuclear momenta.

Poster 16

Signatures of Ion Transport Intermediates in the KcsA Potassium Channel

Ziad Ganim1, Andrei Tokmakoff2, Alipasha Vaziri3

1 Physik-Department E22, Technische Universität München, Garching, Germany

2 Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA

3 Research Institute of Molecular Pathology (IMP) and Max F. Perutz Laboratories (MFPL),

Universität Wien, Wien, Austria

Transmembrane ion channel proteins play an important role in shaping of action potentials

used for neuronal signaling, cardiac muscle activity, and ionic homeostasis[1]. Ion

discrimination and transport through the potassium channel of Streptomyces lividans (KcsA)

is governed by a selectivity filter region, which is conserved across all potassium channels,

and makes KcsA an important model system. To cross the ion channel, potassium must shed

its solvation shell, and is through to proceed through H2O/K+/H2O/K+ and K+/H2O/K+/H2O

ligation intermediates. Despite the availability of a crystal structure[2], there is no definite

mechanistic model for how these solvation changes are combined with very high throughput

rates close to the diffusion limit (108 ions/s)[3] and strong discrimination against other ions

(1:104 vs. Na+)[2]. Quantum coherence effects have been suggested to play a driving role[4].

To help design transient 2DIR experiments studying the structure and dynamics of ion

transport intermediates, molecular dynamics simulations were performed of the KcsA ion

channel with different potassium and water configurations. The amide I FTIR and 2D IR

spectra were calculated to reveal signatures of ion binding. Due to the size of the ion channel

(412 residues), a block-diagonalization procedure was used for computational efficiency,

which makes KcsA the largest protein to have its 2DIR spectrum calculated. A key finding

was that bound potassium increases the rigidity of the protein and causes the spectra to

narrow. However, due to the size of KcsA, switching between the potassium ligation states

caused only subtle changes to the spectrum. Spectral calculations were used to test whether

introducing 13C-18O labels could enhance the changes between different potassium-bound

states. The spectra for all 32 possible isotope-labeling combinations of the selectivity filter

were calculated and two combinations were found to clearly report on the potassium

configuration. Since it is quite labor-intensive and costly to incorporate isotope labels in

membrane proteins, it is worthwhile the use accurate calculations to help design the

experiment.

References:

[1] L. A. Pardo, Physiology, 19 (2004), 285-292.

[2] D. A. Doyle, et al., Science, 280 (1998), 69-77.

[3] E. Gouaux, R. MacKinnon, Science 310 (2005), 1461.

[4] A. Vaziri, M. B. Plenio, New Journal of Physics, 12, (2010), 085001. Poster 17

Heterogeneous dynamics of liquid water by ultrafast vibrational

spectroscopy (3D-IR) and complex network analysis

Sean Garrett-Roe1, Fivos Perakis1, Francesco Rao2, Peter Hamm1

1 Institute of Physical Chemistry, University of Zurich, Zurich, Switzerland.

phamm@pci.uzh.ch

2 Freiburg Institute of Advanced Studies (FRIAS), University of Freiburg, Freiburg, Germany

Our understanding of the structural dynamics of water on the femtosecond to picosecond

timescales comes from the combination of ultrafast infrared spectroscopy and molecular

dynamics (MD) simulations. I will describe a new extension of infrared spectroscopy, three-

dimensional infrared spectroscopy (3D-IR). The 3D-IR measurements of HOD in H2O at

room temperature reveals heterogeneous structural relaxation dynamics on the sub-

picosecond timescale. [1] Complex network analysis of MD simulations [2] shows that this

heterogeneity in structural relaxation timescales stems from different hydrogen bonding

networks extending into the second solvation shell.

References:

[1] S. Garrett-Roe, F. Perakis, F. Rao, and P. Hamm J. Phys. Chem. B (submitted).

[2] F. Rao, S. Garrett-Roe, and P. Hamm J. Phys. Chem. B 114 (2010) 15429.

Poster 18

Excited State Vibrational Analysis of N,N’-Dioctyl Perylene Diimide and its

Anion

Lynetta M. Mier1, Evgeny O. Danilov1, Arthur J. Epstein2, Terry L. Gustafson1

1 The Ohio State University, Department of Chemistry, gustafson.5@osu.edu 2 The Ohio State University, Departments of Chemistry and Physics

N, N’-dioctyl perylene diimide (PDI-C8) and other perylene diimide derivatives have been

proposed to be used as the electron transporting material in organic photovoltaics due to their

high electron mobility and their formation of ordered structures through self assembly

methods.1 In order to characterize the electron transfer mechanisms in organic photovoltaic

systems using PDI-C8 as the electron accepting material, it is necessary to characterize both

the ground and excited state of the neutral compound and its anion. Using femtosecond

stimulated Raman spectroscopy and time resolved infrared spectroscopy, we have observed

the ground and excited state Raman (Figure 1) and IR spectra of PDI-C8 and its anion.

Figure 1 a) Ground state FSRS spectra, Raman pump 565 nm (red), 580 nm (blue), 605 nm (green).

b) Excited state FSRS spectra at 720 nm with 800 nm Raman pump and 480 nm actinic pump -0.1 ps delay (red) and 0.5 ps delay (black). CHCl3 (solvent) band at 1215 cm-1 is marked with an astrisk for both the ground and the excited state.

References:

[1] J.H. Park, A.R. Carter, L.M. Mier, S.A.M. Lewis, R.P. Nadyala, Y. Min, A.J. Epstein;

Advanced Materials 2010 (submitted)

Poster 19

Time-resolved vibrational spectroscopy of [FeFe]-hydrogenase active site

model compounds

Glenn A. Van Meter, Jamie L. Bingaman, Christopher J. Stromberg PhD, Edwin J. Heilweil

PhD. Department of Chemistry and Physics, Hood College, Frederick, MD, United States;

Optical Technology Division, National Institute of Standards and Technology, Gaithersburg,

MD, United States

Some biological systems use [FeFe]-hydrogenases to reduce hydrogen, a step necessary in

hydrogen fuel technology. Model compounds have been found to mimic the active site of

these enzymes. Fe2(S2C3H6)(CO)6 and Fe2(S2C2H4)(CO)6 have been synthesized and their

time-dependent behavior has been observed using ultrafast UV pump/IR probe measurements

of the carbonyl region. Using 266 and 289 nm pump wavelengths, the transient signals have

been assigned to the long-lived loss of a CO ligand (out to 500 ns). Using 355 and 532 nm

pump wavelengths, a short-lived signal ( ~ 150 ps) is observed in addition to the CO loss.

This signal is small in the 355 nm data and much larger in the 532 nm data. It is assigned to a

photoproduct resulting from the breaking of the Fe-Fe bond. If light-driven catalysis is

considered (similar to Photosynthesis II), this bond breaking process could significantly affect

the reaction mechanism.

Poster 20

A compact implementation of Fourier transform 2D-IR and transient 2D-

IR spectroscopy without phase ambiguity

Jan Helbing, Mathias Hausherr, Peter Hamm

1 Physikalisch chemisches Institut, Winterthurerstrasse 190, 8057 Zürich, Switzerland

An optimized setup for time-domain two-dimensional infrared spectroscopy is presented,

which can be implemented at low additional cost and with standard optics in any laboratory

equipped for femtosecond mid-IR spectroscopy1. An interferometer produces a pair of

collinear pump pulses, whose interferogram is simultaneously recorded, and directly yields

their relative phase needed for the calculation of absorptive 2D-IR spectra. Fast coherence

time scanning and population time modulation are introduced as an alternative to the use of

choppers in the suppression of scatter2. The setup was extended in a straightforward manner

for the measurement of transient 2D-IR spectra. We discuss details of the data acquisition

procedure and compare the technique to 2D-IR spectroscopy in the frequency domain3 and in

the boxcars geometry4.

References:

[1] J. Helbing and P. Hamm, J. Opt. Soc. Am. B 28 (2011), 171.

[2] L. P. DeFlores, R. A. Nicodemus, and A. Tokmakoff, Opt. Lett. 32 (2007), 2966.

[3] J. Bredenbeck, J. Helbing, and P. Hamm, J. Chem. Phys. 121, (2004) 5943.

[4] H. S. Chung, M. Khalil, A. W. Smith, and A. Tokmakoff, Rev. Sci. Inst. 78 (2007),

063101.

Poster 21

Optimization of the Pr phytochrome photoisomerization by pre-twisting of

the chromophore ground state: A polarization resolved fs VIS pump – IR

probe study

Yang Yang1, Martin Linke1,Ricardo Matute2, Leticia Gonzalez2, Peter Schmieder3, Karsten

Heyne1

1 Free University Berlin, Department of physics, Arnimallee 14, 14195 Berlin, Germany

21 Friedrich-Schiller Universität Jena, Institut für Physikalische Chemie, Helmholtzweg 4,

07743 Jena, Germany

3 Leibniz-Institut für Molekulare Pharmakologie, Robert-Rössle Str. 10, 13125 Berlin,

Germany

Z-to-E photoisomerization the protein bound chromophore PCB in Pr Cph1 phytochrome

is the origin of signaling response. By polarization resolved femtosecond visible pump –

infrared probe spectroscopy the structural dynamics of Z-to-E photoisomerization in Pr

phytochrome from cyanobacterium Synechocystis 6803 is followed in real time (fig.1).

Orientational changes of ring D’s vibrational C19=O transition dipole moment in the

electronically excited state reveal rotation of ring D in the electronically excited state with a

time constant of 30 ps. Heterogeneity of the chromophore structure in the protein allows to

observe that a pre-twisted chromophore structure exhibits seven times higher isomerization

quantum yield than a more planar structure. Symmetry breaking by the protein surrounding

seems to be one of the essential ingredients to optimize photoreactions.

Figure 1: Model of the PCB ZZZssa chromophore geometry with its electronic (black) and

vibrational (red) transition dipole moment within the molecular structure.

Poster 22

x

y

zEP

ES

pump

x

y

zEP

ES

pump1.00

0.99

0.98

0.97

0.96

norm

aliz

ed d

iffer

entia

l SF

G in

tens

i

400020000delays (fs)

S-pumped

P-pumped

Ultrafast Reorientation of Dangling O-H Groups at the Air/Water Interface

Cho-Shuen Hsieh1, Kramer Campen1, Ana Celia Vila Verde2, Peter Bolhuis2, and Mischa

Bonn1

1 hsieh@amolf.nl, campen@amolf.nl, bonn@amolf.nl, FOM Institute for Atomic and

Molecular Physics (AMOLF), Science Park 104, 1098 XG Amsterdam, The Netherlands.

2 A.C.AraujoVilaVerde@uva.nl, bolhuis@uva.nl, Van 't Hoff Institute for Molecular Science,

University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands

Owing to the ubiquity of water, many studies exist of the (sub-) picosecond structural

dynamics of water molecules in the bulk liquid. In contrast, information on the dynamics of

interfacial water has been lacking, due to the difficulty in investigating the dynamics of

specifically the outermost water monolayer(s). We overcome this challenge by employing

ultrafast, polarization-resolved IR pump / vibration sum frequency probe spectroscopy [1] to

reveal the dynamics of O-H groups sticking out of the water surface, into the gas phase.

Because the orientational distribution of excited dangling OH groups is a function of pump

polarization (Fig.1 (a)), we can track the reorientation of these dangling OH groups in real

time by measuring the relaxation of different pump/probe signals at multiple polarizations

(Fig.1 (b)) and applying an appropriate model [1]. Reorientation of interfacial OH groups

occurs on sub-picosecond timescales, appreciably faster than in bulk water.

(a) (b)

Fig. 1 (a) Experimental geometry and schematic orientational distributions of subensembles of dangling OH groups that are excited by the pump pulse at time t=0 using S-(blue) and P-(red) polarized pump light. (b) Time-resolved SFG data for interfacial water with pump = probe = 3700 cm-1. By comparing how the differently pumped subensembles relax we can quantify both the rotational motion (~800fs/rad2) and vibrational relaxation (~850fs) of the dangling O-H.

References:

[1] H.-K. Nienhuys and M. Bonn, J. Phys. Chem. B 113 (2009) 7564-7573.

Poster 23

Salt Bridge Interactions in Solution Probed Using Two-Dimensional

Vibrational Spectroscopy

A. Huerta Viga1, A. Rupenyan2, S. Woutersen3

Van 't Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam

Science Park 904, 1098 XH Amsterdam, The Netherlands 1A.HuertaViga@uva.nl 2alisa.rupenyan@gmail.com 3S.Woutersen@uva.nl

Salt bridges are attractive electrostatic interactions between charged side chains of different

amino acids. They play an important role in the stability of the secondary and tertiary

structure of many peptides and proteins. Here, we demonstrate how two-dimensional

vibrational spectroscopy (2D-IR) can be used to probe the salt-bridge interactions between

Glutamic Acid (Glu) and Arginine (Arg), see Fig. a. To probe this salt bridge, we measure the

vibrational coupling between normal modes of the carboxylate side group of Glu and the

guanidinium side group of Arg. The cross-peak anisotropies are directly related to the salt-

bridge geometry. We demonstrate our method for three different α-helical peptides. Figs. b

and c show the FTIR and 2DIR spectra of C-peptide. There is controversy about the existence

of the Glu2:Arg10 salt bridge in this peptide: previous experimental work showed that this

salt bridge was dominantly responsible for the helix stability [1], while recent MD simulation

suggested that Glu2 and Arg10 were hardly interacting [2]. However, we measured significant

cross-peak intensities between Glu2 and Arg10 (see Fig. d), which provides unambiguous

evidence for a Glu:Arg salt bridge in the folded C-peptide.

References:

[1] Fairman R, et al., Biophys Chem 37 (1990) 107.

[2] Khandogin J, et al., Proc Natl Acad Sci USA 103 (2006) 18546

Poster 24

Effect of Protons and Hydroxide Ions on the Dynamics of Water

J. Hunger, K.-J. Tielrooij, M. Bonn, H. J. Bakker

FOM-Institute Amolf, Science Park 104, 1098 XG Amsterdam, The Netherlands

Despite the fact that acidic and alkaline solutions are often referred to as “mirror systems”

(i.e. a proton and a proton hole), recent theoretical studies indicated some remarkable

differences between the properties of the proton (H+) and the hydroxide (OH-) ion in aqueous

solution. It was calculated that protons and hydroxide ions have distinctly different hydration

structures and conduction mechanisms [1].

We study the influence of protons (H+)

and hydroxide ions (OH-) on the dynamical

and structural properties of the solvating

water molecules using polarization-resolved

femtosecond infrared pump-probe and

transient Terahertz spectroscopy. We observe

some striking differences in the dynamics of

these systems. The results indicate that the

vibrational life time of the OH stretch

vibrations of water is rather unaffected in an

acidic environment [2], but gets significantly

shortened in an alkaline environment. The

dielectric response measured with Terahertz spectroscopy shows that there is no rigid

hydration structure around the hydroxide ion whereas for the acidic solutions it is found that

the proton forms a so-called Eigen complex (H9O4+) in which ~4 water molecules are tightly

bound to the proton [3]. Furthermore, we find that the transfer of the charge of the proton

through the water liquid involves the reorientational motion of ~15 surrounding water

molecules. For the hydroxide this number is smaller by a factor of 2.

Hence, our results show that the aqueous proton and aqueous hydroxide ion can indeed not

be viewed as each other mirror image, in agreement with recent theoretical predictions, and

that acidic and alkaline solutions strongly differ on a molecular scale.

References:

[1] D. Marx, A. Chandra, M. E. Tuckerman, Chem. Rev. 110 (2010) 2174.

[2] R. L. A. Timmer, K.-J. Tielrooij, H. J. Bakker, J. Chem. Phys. 132 (2010) 194504.

[3] K.-J. Tielrooij, R. L. A. Timmer, H. J. Bakker, M. Bonn, Phys. Rev. Lett. 102 (2009)

198303.

Poster 25

1500 1600 1700 1800 1900 2000

-10

0

10

20

1500 1600 1700 1800 1900 2000

-10

0

10

20

A

Wavenumbers [cm-1]

O

D [

mO

D]

0.8 ps 1.0 ps 2.0 ps 3.0 ps 4.0 ps 8.0 ps 32.0 ps ATR B

Wavenumbers [cm-1]

Vibrational Relaxation in Aqueous Formamide

Sidsel Dahl Schrøder1, Jan Thøgersen1, Paola Sassi2, Henrik G. Kjaergaard3, and Søren Rud

Keiding1

1 Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark,

2 Department of Chemistry, University of Perugia, 06123 Perugia, Italy

3 Department of Chemistry, University of Copenhagen, DK 2100 København Ø, Denmark

keiding@chem.au.dk

We have studied the vibrational relaxation of formamide (CHOND2) in water (D2O) using

UV-IR femtosecond transient absorption spectroscopy. Following excitation of the n*

transition at 200 nm, formamide dissociates along the C-N bond. However, due to caging by

the solvent ~80% of the molecules geminately recombine to the electronic ground state of

formamide. This leaves a large amount of vibrational energy to be dissipated. We have

followed the vibrational energy by monitoring the transient absorption of the three prominent

vibrational transitions at 1352 cm-1, 1400 cm-1, and 1666 cm-1 representing the motion of the

C-N, C-H, and C=O bonds, respectively. In the figure the transient absorption corresponding

to the carbonyl stretch at 1666 cm-1 is

shown (A) together with a simulation (B)

based on vibrational energy relaxation

(VER) mediated by cascading down the

vibrational levels of the carbonyl stretch,

vi→vi-1→vi-2……→v=0. However, an

alternative VER model based on

anharmonic coupling to low frequency

modes is also able to reproduce the observed

transient. In addition, we measured the temperature dependence of the static IR spectrum of

formamide and obtained anharmonic constants for formamide using overtone spectroscopy.

In the contribution we will discuss the different models for vibrational energy relaxation and

the observational consequences of the cascade model and the anharmonic coupling model.

Poster 26

Dynamics near the Glass Transition: Using 2DIR to Study Dynamic

Heterogeneity

John T. King, Matthew R. Ross and Kevin J. Kubarych

Department of Chemistry, University of Michigan, 930 North University Avenue. Ann Arbor,

Michigan, 48109, USA

email: kubarych@umich.edu

Ultrafast two-dimensional infrared spectroscopy (2DIR) has emerged as a powerful tool

for studying condensed phase dynamics through the experimental measure of the frequency-

frequency correlation function (FFCF).1 We have previously used 2DIR to study the solvation

environment of linear alcohol solvents solvating a metal carbonyl vibrational probe.2 Here, we

use a similar vibrational probe to study the complex dynamics presented by a fragile glass

near its glass transition temperature, Tg.

Fragile glasses have been the subject of extensive studies, yet a uniform and complete

description of the dynamics is still lacking. We focus on dirhenium decacarbonyl, DRDC, in

1,2-hexanediol as the system is cooled towards its glass transition temperature. Fig. 1 shows

the stretched exponential (=0.33) spectral diffusion time

constants as a function of viscosity. Despite no observable

lineshape changes, approach to the glass transition is

marked by anomalous diffusion, non-exponential spectral

diffusion, and a breakdown of a simple Arrhenius law

framework. Observing such slow spectral dynamics is due

in large part to the long vibrational lifetime of the metal

carbonyl probe. These observations are consistent with the

emergence of dynamical heterogeneity, where spatial

heterogeneity and cooperative rearrangement of spatially

distinct domains act to prolong the frequency correlation

times. We hope to gain a better understanding of other complex heterogeneous environments

such as those found in proteins, which display dynamics that are analogous to the dynamic

mosaic model of glasses.3

References:

[1] Khalil M, Demirdöven N, Tokmakoff A, J. Phys. Chem. A 107 (2003) 5258-5279.

[2] King JT, Baiz CR, Kubarych KJ, J. Phys. Chem. A 114 (2010) 10590-10604.

[3] Frauenfelder H, Fenimore PW, Chen G, McMahon BH, PNAS 103 (2006) 15469-15472.

Poster 27

Figure 1. Spectral diffusion of DRDC in 1,2-hexanediol. (Inset) Arrhenius plot of the temperature dependent dynamics.

Investigation of low frequency vibrations by time-frequency analysis of dispersed fs –FWM

G.. Knopp1, P.P. Radi 1 and T. Gerber 1

1Paul Scherrer Institute, Villigen, Switzerland

Electronically resonant fs - FWM provides a variety of options to probe molecular dynamics

according to the temporal sequence of involved ro-vibronic dipole transitions1. Sub-processes

arising from different molecular states possibly contribute at different frequencies to the

signal and valuable information is accessed using a dispersed detection method. Signal

dispersion in electronically off-resonant fs - FWM can also unveil contributions that are

masked in a one dimensional measurement2. Raman-type processes are adequate for

investigating ro-vibrational modes in the ground electronic state and the high peak-power

output of fs-lasers facilitates the excitation of weak Raman coherences. Approaching low

frequency vibrations, such as torsion- and bending modes with energies less than 200 cm-1,

involves spectrally overlapping pump and Stokes pulses

and the method becomes degenerate (fs-DFWM). When

passing through a spectrometer the signals are

temporally stretched and distinct contributions can

overlap and interfere on the detector. The observed

partially ‘self-heterodyned’ interference patterns are

expected to contain information not only on the

rotational properties but also on simultaneously excited

low-frequency vibrations. Dispersed fs-FWM signals of

alkyl-benzenes and of di-tert-butyl peroxide have been

measured and analyzed with respect to low frequency

vibrations.

References:

[1] A. M. Walser, M. Meisinger, P. P. Radi, T. Gerber and G. Knopp, Physical Chemistry

Chemical Physics, 11, (2009) 8456-8466.

[2] G. Knopp, Y. Sych, P.P. Radi and T. Gerber, Journal of Raman Spectroscopy, accepted,

(2011).

Poster 28

Figure: Dispersed fs-DFWM signal from gaseous di-tert-butyl peroxide and Fourier analysis as function of the off-center detection frequency.

Fig. 1 Ring closing reaction of a photochromic spiropyran in D2O.

Spiropyrans in aqueous media

Kohl-Landgraf, J.1, Gonçalves, D.2, Heckel, A.2, Wachtveitl, J.1 1 Goethe-Universität Frankfurt a. M., Institut für Physikalische und Theoretische Chemie,

landgraf@theochem.uni-frankfurt.de, wveitl@theochem.uni-frankfurt.de 2 Goethe-Universität Frankfurt a. M., Cluster of Excellence Macromolecular Complexes,

goncalves@biochem.uni-frankfurt.de, heckel@uni-frankfurt.de

Spiropyrans are photochromic molecules consisting of two orthogonal ring systems that can

be switched between two states by means of light. By irradiating a spiropyran with UV light

one of the ring systems is opened up leading to a planar molecular structure which is called

the merocyanine form. The opening process can be reversed by irradiating the merocyanine

with visible light.

Even though the photochemical behavior of spiropyrans in different solvents is well

investigated [3], only one very recent study exists that deals with the behavior in water, which

is crucial for biological applications [4]. Thus a set of water soluble

spiropyrans was designed to optimize spectral properties,

photostability, switching efficiency and reaction pathway.

We present steady state and fs-transient absorption studies in the

infrared and visible spectral range revealing the behavior of the

compounds in D2O and H2O respectively. The interconversion

between the two forms is reversible without degradation after a few

cycles and both the closing and the opening reaction is accomplished

on the low picosecond timescale (Fig. 1).

References:

[1] Holm, A.-K., Rini, M., Nibbering, E.T.J., Fidder, H., Chem. Phys. Lett. 376 (2003) 214-

219.

[2] Holm, A.-K., Mohammed O.F., Rini, M., Mukhtar, E., Nibbering, E.T.J., Fidder, H., J.

Phys. Chem. A 109 (2005) 8962-8968.

[3] Minkin V.I., Chem. Rev., 104 (2004) 2751-2776.

[4] Shiraishi, Y., Itoh, M., Hirai, T., Phys. Chem. Chem. Phys. 12 (2010) 13737–13745

Poster 29

Dependence of Vibrational Coherence Dynamics in all-trans retinal in

Bacteriorhodopsin on excitation wavelengths

J.P. Kraack1, T. Buckup1, and M. Motzkus*1

1Physikalisch-Chemisches Institut, Ruprecht-Karls Universität Heidelberg, D-69120 Heidelberg, Germany, *E-Mail: marcus.motzkus@pci.uni-heidelberg.de

Bacteriorhodopsin (BR) is a membrane protein from Halobacterium salinarum, which is

responsible for bacterial photosynthesis. Photon-absorption induces an isomerization process

of a protein-bound retinal photoreceptor in less than one picosecond after excitation [1]. Much

attention in ultrafast investigations on this isomerization has always been attracted by the

observation high-frequency (> 800 cm-1) and low-frequency (< 800 cm-1) wave packet

dynamics in time-resolved signals [2-4]. Here, we investigate vibrational coherence dynamics

in retinal’s electronic ground- and excited states by means of spectrally resolved Degenerate

Four-Wave-Mixing and how these dynamics depend on the excitation spectrum. Excited state

wave packet dynamics, which consist of out-of-plane and low-frequency modes are observed

over a broad spectral range of signal detection. Low-frequency modes are observed in two

spectral regions of excited state absorption for the first time, resolving a long standing

inconsistency in the femtosecond dynamics of the isomerization. We show that the

observation of excited state coherences depends on the excitation wavelength, indicating an

excitation mechanism via internal vibrational energy redistribution.

Figure: Excitation spectra and resulting DFWM signal dynamics in BR.

References:

[1] R.A. Mathies et al., Science 240, 777 (1988). [2] S.L. Dexheimer et al., Chem. Phys. Lett. 188, 61 (1992). [3] A. Kahan et al., J. Am. Chem. Soc. 129, 537 (2007). [4] T. Kobayashi et al., Nature, 414, 531 (2001).

Poster 30

Ultrafast Excited-State Structural Dynamics in Photoactive Yellow Protein

Chromophore Revealed by Tunable UV-Femtosecond Stimulated Raman

Spectroscopy

Hikaru Kuramochi1, 2, Satoshi Takeuchi1, Tahei Tahara1

1 Molecular Spectroscopy Laboratory, Advanced Science Institute (ASI), RIKEN, 2-1

Hirosawa, Wako 351-0198, Japan

2 Department of Chemistry and Materials Science, Tokyo Institute of Technology, 2-12-1

Ohokayama, Meguro-ku 152-8551, Japan

e-mail: h.kuramochi@riken.jp

Blue-light absorption by the trans-p-coumaric acid (pCA) choromophore of Photoactive

Yellow Protein (PYP) leads to trans-to-cis isomerization, triggering a signaling cascade,

which ultimately results in negative phototaxis of the purple bacterium Halorhodospira

halophila [1]. However, the most essential

initial photodynamics, the trans-to-cis

isomerization of pCA, has yet to be fully

understood. Here we address this topic by means

of femtosecond stimulated Raman spectroscopy

(FSRS). As a key device for this study, an

optical parametric amplifier for the generation

of narrow-band UV pulse was developed

because excited-state absorption of trans-pCA

appears exclusively in the UV region. Obtained

UV-FSRS spectra showed significant temporal

change within 1 ps after the excitation,

suggesting substantial ultrafast structural change

in the excited-state of PYP chromophore.

References:

[1] K. J. Hellingwerf, J. Hendriks, T. Gensch, J. Phys. Chem. A 107 (2003) 1082.

Poster 31

Fig. 1. UV-FSRS spectra of trans-pCA in phosphate buffer solution (pH=7).

Shaping SFG: advantages of mid-IR pulse shaping for heterodyned and

time-domain data collection

Jennifer E. Laaser1, Wei Xiong1, Martin T. Zanni1

1 University of Wisconsin-Madison, Department of Chemistry, jlaaser@chem.wisc.edu

Pulse shaping is proving to be a valuable method

for collecting multidimensional IR and visible

spectra. Here, I will present a new application of

mid-IR pulse shaping to heterodyne-detected sum-

frequency generation (SFG) spectroscopy, which

has many advantages over conventional SFG

techniques. By scanning in the time domain (TD)

with all femtosecond pulses, we obtain SFG spectra

with much higher lineshape fidelity than in the

broadband frequency-domain (FD) method, and with resolution that can be increased almost

arbitrarily by extending the scan range.[1] We utilize the pulse shaper to cycle pulse phases

and delays on a shot-to-shot basis, allowing each full scan of the free-induction decay to be

acquired in approximately 0.4 s. Additionally, pulse shaping allows phase cycling for data

collection in the rotating frame and shot-to-shot background subtraction. These advantages

enable rapid data acquisition, minimizing spectral distortions due to long-term laser

fluctuations. We demonstrate this method for an aryl isocyanide on gold and discover that the

molecules have an inhomogeneous distribution that was not previously resolved with the

more common broadband frequency-domain SFG technique. Since the pulse shaper can

easily generate more complex pulses as well, we anticipate that pulse shaping will enable

future experiments in multidimensional surface-sensitive spectroscopy and time-resolved

kinetics.

References:

[1] Laaser, J. E.; Xiong, W.; Zanni, M. T., J. Phys. Chem. B, submitted.

Poster 32

Transient Infrared Spectroscopy: A new approach to investigate Valence Tautomeric Interconversion

Lapini, A.1; Tourón Touceda, P.1; Mosquera Vázquez, S.1; Lima, M.1

Dei, A.2; Righini, R.1

1European Laboratory for Non Linear Spectroscopy (LENS), University of Florence,

Via Nello Carrara 1, 50019 Sesto Fiorentino , Italy. 2LAMM Laboratory, Dipartimento di Chimica dell’ Università di Firenze, UdR INSTM, Via

della Lastruccia 3, 50019 Sesto Fiorentino (Firenze), Italy

Molecules that demonstrate intramolecular electron transfer accompanied by a single-site spin

crossover are termed valence tautomers. An appealing situation is encountered when the

redox moieties are different, a situation found in cobalt-dioxolene complexes undergoing

valence tautomerism (VT). The phototriggered processes occur with a well-defined

mechanism that couples the electronic ground state of the chromophore to the electronic

excited states. The practical application of this phototriggered event is, however, intrinsically

related to the whole duration of the photophysical processes (internal conversion, intersystem

crossing and vibrational relaxation) involved in the relaxation of the perturbed chromophore.

The goal of this work is of establishing the time scale of the photoinduced valence tautomeric

interconversion and the characterization of the relaxation pathways in a 1:1 cobalt-dioxolene

system. Amongst the series of cobalt complexes [Co(Mentpa(diox)]PF6 (diox=3,5-di-tert-

butyl-1,2 dioxolene; tpa=tris(2-pyridylmethyl)amine) the Me0 and Me3 are investigated by

ultrafast transient infrared spectroscopy. For Me0, the stable form has catecholate (CAT)

charge distribution of the dioxolene moiety, whereas the incorporation of three CH3 groups in

the ancillary ligand (tpa) results in the stabilization of the semiquinonate (SQ) form as the

ground state at room temperature. The first part of the work is dedicated to the identification

of the spectroscopic features of the SQ and Cat tautomers by means of DFT frequency

calculation, so that they can be distinguished from each other in the time-resolved optical

experiment. Photo-excitation of [CoIII(Me0tpa)Cat]+ results in the ultrafast population of a

long lived excited state. The comparison of 1 ns transient infrared spectrum with the

calculated difference spectrum and with the (Me3 - Me0) difference spectrum allows us to

unequivocally identify the long lived excited state as ([CoII(Me0tpa)SQ]+)*. This is the first

time, to our knowledge, that transient infrared spectroscopy is applied to study the

photoinduced valence tautomerism process in cobalt-dioxolene complexes.

Poster 33

Finding order in disordered peptides: A 2D IR study of the structure and dynamics in elastin-like peptides

Joshua Lessing1, Santanu Roy2, Kevin Jones1, Mike Reppert1, Chunte Sam Peng,1 Jongjin Kim1, Dominik Marx3, Thomas L. C. Jansen2, Jasper Knoester2, and Andrei Tokmakoff1

1 Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue,

Cambridge, MA 02139 USA

2 Center for Theoretical Physics and Zernike Institute for Advanced Materials, University of

Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands

3 Lehrstuhl fur Theoretische Chemie, Ruhr-Universität Bochum,

44780 Bochum, Germany Elastin is a ubiquitous viscoelastic protein that is responsible for providing the restoring force

for organs after mechanical deformation. Upon heating, elastin and its mimics, termed elastin-

like peptides, undergo an inverse temperature transition from an extended to a folded state.

To date no consensus has been reached on the structure of the protein or the molecular origin

of its phase transition. This dearth of molecular level information is due to two factors: 1)

elastin is amorphous, making it impossible to create a sample for X-ray crystallography and

2) elastin's conformational motions take place on a sub-nanosecond timescale making it

impossible to resolve its conformational heterogeneity with NMR. In contrast, two

dimensional infrared (2D-IR) spectroscopy does not suffer from these limitations and

therefore is an ideal technique for this system. We have performed temperature and salt

dependent FT-IR and 2D-IR spectroscopy on a library of nine 13C/18O Amide I isotopologues

of the canonical single turn elastin mimic GVGVPGVG. Isotope labeling in conjunction with

2D-IR has made it possible to obtain site specific time resolved experimental data. This data

was interpreted using a structure-based spectroscopic model which included a new

parametrization scheme for the amide I vibration of proline. Here we present a detailed

experimental and theoretical study of GVGVPGVG, providing the first experimentaly based

description of the structure and dynamics of this class of peptides. Size dependent studies of

the GVG(VPGVG)n oligomers will also be presented.

Poster 34

Proton Transport in Biological Systems can be Probed by Two-dimensional

Infrared Spectroscopy

Chungwen Liang, Thomas la Cour Jansen, and Jasper Knoester

Center for Theoretical Physics and Zernike Institute for Advanced Materials University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands

C.liang@rug.nl

Proton transport in biological systems plays a crucial role on maintaining cellular life.

However, with the traditional experimental approaches one cannot obtain mechanistic

information on the molecular level due to the limitation in both spatial and time resolutions.

Two-dimensional infrared spectroscopy (2DIR) is a promising method to reveal ultra-fast

dynamics [1]. In the present work, we focus on proton transport through the Gramicidin A

channel and model the amide-I region of the 2DIR spectrum theoretically to examine its

sensitivity to the proton transport process. We show that one can expect that the time

evolution of the 2DIR spectrum gives insight into this process, and suggest an experimental

method to determine the proton transfer rate inside the protein channel [2].

References:

[1] P. Hamm and M. Zanni. Concepts and Methods of 2D Infrared Spectroscopy. Cambridge

University Press.

[2] C. Liang, T.L.C. Jansen, and J. Knoester. J. Chem. Phys. 134 (2011) 044502.

Poster 35

Novel Natural and Artificial Side Chains Sensitive to Protein Hydration

Detected by Infrared and Raman Spectroscopy

Casey H. Londergan1, Alice R. Vienneau, Shannon R. Dalton, Kevin M. Hoffman

1Haverford College, Haverford, PA USA, clonderg@haverford.edu

The presence, absence, and dynamics of water at specific sites on the surface of proteins

are intrinsic to proteins’ ability to fold and function correctly and to bind to their natural target

susbtrates. Several examples of hydration-sensitive vibrations located on amino acid side

chains are presented here, including both naturally occurring and artificial amino acids. The

dependence of each of these bands on local hydration is qualitatively different, so they can

each be used in complementary ways to report on local hydration. Strongly Raman-active

vibrations to be discussed include the S-H band of protonated cysteine and the C-D(2)

vibration of histidine, which can each report on protonation and effective pH in enzymatic

active sites. IR-active vibrations include the CN stretching band of cyanylated cysteine,

which is sensitive to electrostatics, H-bonding, and ps solvent dynamics, and the asymmetric

NNN stretching band of covalently bound azide, which is sensitive mainly to hydration. The

different responses of these vibrations are explored in the context of enzymes, membrane-

active proteins, and intrinsically disordered proteins as they undergo binding to natural

targets.

Poster 36

Direct Evidence that Flavin Photoexcitation Modulates the Chromophore

Environment in AppA on the Ultrafast Timescale

Andras Lukacs 1, Allison Haigney2, Rui-Kun Zhao1, Richard Brust2, Greg Greetham3, Ian

Clark3, Mike Towrie3, Peter J. Tonge2, Stephen R. Meech1

1 School of Chemistry, University of East Anglia, UK a.lukacs@uea.ac.uk

2 Department of Chemistry, Stony Brook University, US 3Central Laser Facility, Harwell Science and Innovation Campus, UK

AppA is a BLUF protein which serves as a transcriptional anti-repressor found in

Rhodobacter sphaeroides [1]. Similarly to other flavoproteins the absorption of the photon is

may be followed by an electron transfer cascade [2], but the same time the hydrogen-bond

network around FAD undergoes to a reorganization which is crucial for the formation of the

light adapted state of the protein [3].

In this work the photoinactive Q63E mutant was constructed to modulate the hydrogen

bonding pattern between the key glutamine residue (Q63) and FAD. The figure shows the

TRIR spectra of dark, light and Q63E AppA taken at 3 ps; the inset shows the spectra of

Q63E and 13C labelled Q63E. The latter one proves that the vibrational mode observed at ~

1730 cm-1 is not a flavin but a protein mode. Our experiments shows that this mode appears

within 100 fs after excitation giving direct evidence that the photoexcitation reorganized the

hydrogen bonding network of the flavin chromophore.

References:

[1] Masuda, S., and Bauer, C. E. Cell, 110 (2002) 613-623

[2] Toh et al, Biophys J. 95 (2008), 312–321

[3] Grinstead et al. JACS, 128 (2006) 15066-15067

Poster 37

Time-Resolved Raman Spectroscopy of Intramolecular Vibrational

Redistribution in Terminal Acetylene Molecules.

A. L. Malinovsky1, A. A. Makarov2, and E. A. Ryabov3 1 Inst. of Spectroscopy, RAS, Troitsk, Moscow reg, 142190 Russia, almalino@isan.troitsk.ru 2 Inst. of Spectroscopy, RAS, Troitsk, Moscow reg, 142190 Russia, amakarov@isan.troitsk.ru 3 Inst. of Spectroscopy, RAS, Troitsk, Moscow reg, 142190 Russia, ryabov@isan.troitsk.ru

The dynamics of intramolecular vibrational redistribution (IVR) in terminal acetylene mo-

lecules was investigated. The depopulation of the first initially excited level of H–C vib-

ration (3333 cm–1) was monitored directly with ~10 ps time resolution using spontaneous

Raman technique [1–5]. The rates of this process W were found to lie in a range 0.4109 –

0.91010 s–1; the least of figures measured in trifluoropropyne correspond to the slowest IVR

reported so far. Another feature of the dynamics is an incomplete depletion, especially clearly

pronounced for 'simple' objects: e.g. for propyne at t >> W–1, the share of residual energy

even exceeds the value of 0.5.

A theoretical analysis made it possible to explain on quantitative level many aspects of the

picture described. In particular, the ratio between values of W for subset of 'simple' of our

objects is in agreement with supposition that the doorway state leading to IVR from H−C to a

bath of all vibrational–rotational states consists of one quantum of the C≡C stretch and two

quanta of the H−C≡C bend. Also, that is nontrivial, an assuming about strong vibrational–

rotational mixing in the bath enables to connect the densities of the IVR-effective states

with the pairs {W, } extracted from the experiments.

References:

[1] A.L. Malinovsky, A.A. Makarov, E.A. Ryabov, JETP Lett. 80 (2004) 532

[2] A.L. Malinovsky, Yu.S. Doljikov, A.A. Makarov, N.-D.D. Ogurok, E.A. Ryabov,

Chem. Phys. Lett. 419 (2006) 511

[3] A.L. Malinovsky, A.A. Makarov, E.A. Ryabov, JETP 106 (2008) 34

[4] A.A. Makarov, A.L. Malinovsky, E.A. Ryabov, J. Chem. Phys. 129 (2008) 116102

[5] A.L. Malinovsky, A.A. Makarov, E.A. Ryabov, JETP Lett. 93 (2011) 124

Poster 38

Dependence of the ultrafast initial dynamics of carotenoids on the

conjugation length (N) studied by multidimensional spectroscopy

M. S. Marek1, T. Buckup1 and M. Motzkus1

1 Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, D-69120

Heidelberg, Germany, email: marcus.motzkus@pci.uni-heidelberg.de

Determination of the detailed energy dissipation pathway in carotenoids following

photoexcitation proved to be particularly challenging for optical spectroscopy. Specifically

the question whether additional dark states [1] between the S2 and S1 states participate in the

relaxation is highly controversial. Application of pump-degenerate four wave mixing (pump-

DFWM) to -carotene [2] and lycopene in combination with numerical simulations based on

the Brownian oscillator model already gave strong evidence for an additional electronic state

located energetically below S2 and playing a role in the deactivation process. Here, we further

investigate the interplay between the conjugation length N of carotenoids and the involved

electronic states in the very early dynamics by using pump-DFWM. We concentrate on

carotenoids with N = 10 (spheroidene) and 11 (lycopene), for which a crossing of the S2 state

with dark states is proposed. The two carotenoids differ predominantly in their signal at early

initial pump delays (T < 200 fs). Lycopene shows a long living signal resulting from a

stimulated emission pumping (SEP) DFWM process between the 3Ag- state and a

vibrationally hot ground state. In spheroidene, the 3Ag- state is located above the S2 state.

However, a similar long living signal is observed, but overlaid with an additional rapidly

decaying signal. This complex dynamics is explained by concurrent SEP DFWM between

1Bu- and hot S0 as well as DFWM between 1Bu

- and a higher lying singlet state Sm.

Figure: Pump-DFWM signal of spheroidene, (a) experimental, (b) simulated. (c) Rate model for relaxation used

in the simulations. X represents the 3Ag- state for lycopene and the 1Bu

- state for spheroidene, respectively.

Acknowledgments: We thank Y. Koyama for providing the spheroidene samples.

References [1] Y Koyama et al., Int. J. Mol. Sci. 11, 1888 (2010). [2] T. Buckup et al., Arch. Biochem. Biophys. 483, 219 (2009).

Poster 39

Hydration water dynamics at biological interfaces: peptides and proteins studies

Kamila Mazur, Ismael A. Heisler, Stephen R. Meech

School of Chemistry, University of East Anglia, Norwich NR4 7TJ, UK

The dynamics of water in the hydration shells of biological molecules has been studied

extensively in recent years. Interfacial water molecules differ from bulk water in a number of

ways and play a significant role in many biological processes, e.g. protein folding and the

activity of enzyme proteins. We studied picosecond dynamics and THz spectra of aqueous

solutions of protein and peptides using ultrafast optical Kerr effect spectroscopy.1 To gain

information to which extent hydrophilic and hydrophobic sites affect water mobility

hydrophobic and amphiphilic peptides were chosen2.

We find that both peptide and protein solutions can be divided into two distinct

concentration regimes, below and above 0.4 M and 7 wt. % respectively. At low

concentration the tetrahedral structure of water is largely preserved, but the relaxation time is

significantly increased. At these low concentrations the decrease in water mobility scales

linearly with solute concentration and extrapolates back to the bulk water value. We found

that water in the vicinity of amphiphilic peptide is slower than in the vicinity of the

hydrophobic one, which suggests that hydrophilic sites have the larger effect on water

retardation . At high concentrations the mea relaxation time increases significantly. In this

case solute dynamics may contribute to the observed relaxation. At high concentrations new

band ~90 cm-1 was observed. This band grows linearly with concentration and is associated

with out of plane bending of H-bonded solute.

0 1 2 3 4

1E-4

1E-3

0.01

0.1

1

pump-probe time delay /ps

NAGMA 3M 0.25M 2M 0.12M 1M water 0.5M

a)

0 50 100 150 200 250 300

0.00

0.05

0.10

0.15

0.20

Im {

D(

)}

wavenumber /cm-1

NAGMA 3M 2M 1M 0.5M 0.25M 0.12M water

b)

Figure 1. a) The time resolved Kerr effect signal of NAGMA and b) its frequency domain

representation.

References:

[1] N.A. Smith and S.R. Meech, Int. Rev. Phys. Chem. 2002, 21, 75. [2] K. Mazur, I.A. Heisler, S.R. Meech, J. Phys. Chem. B 2010, 114, 10684.

Poster 40

Artificial amino acids as versatile tools for 2D-IR studies of proteins

H. Müller-Werkmeister1, Y.-L. Li1,3, E.-B. W. Lerch1,4, D. Bigourd1,5, S. Eger2, A. Marx2 and J. Bredenbeck1*

1Institute for Biophysics, Goethe-University, 60438 Frankfurt, Germany;

2Institute for Organic Chemistry, University of Konstanz, 78457 Konstanz, Germany; 3Present address: Department of Chemistry, University of Iowa, Iowa City, Iowa 52242,

USA; 4 Present address: Wiley-VCH Verlag GmbH & Co. KGaA, 69469 Weinheim, Germany; 5Present address: Blackett Laboratory, Imperial College, London SW7 2BZ, UK

Time-resolved 2D-IR spectroscopy has been established as a sensitive tool for studying

ultrafast molecular dynamics in real-time. However, when 2D-IR spectroscopy is applied to

proteins the many similar oscillators in the protein backbone and amino acids side chain have

spectrally overlapping signals, which limits the ability to obtain local, site-selective

information. An approach to potentially overcome this problem is the use of infrared labels

with functional groups that have absorbtion bands that are well-seperated from absorptions

present in native proteins. Recent developments in molecular and chemical biology [1] offer a

new alternative to classical post-translational chemical modifications, the incorporation of

artificial amino acids with functional groups such as azides or nitriles site-selectively and co-

translationally.

Here, we use two-color 2D-IR spectroscopy [2] to investigate the spectral characteristics of

and energy transfer times between functional groups in different artifical amino acids. The

artificial amino acids chosen are promising candidates for further studies of structural

dynamics in proteins. The simultaneous use of two independently tunable optical parametric

amplifiers for IR-light generation permits the observation of time-dependent transfer cross-

peaks between vibrations that are widely separated in the spectrum. The experiments show a

clear correlation between energy transfer times and the physical distance between functional

groups involved in the process, indicating that vibrational energy transfer times provide

insight into the molecular structure and the proximity of functional groups to one another.

Structural constraints for the investigation of protein dynamics could be obtained with time

resolution of several picoseconds.

References:

[1] L. Wang, J. Xie, P. G. Schultz, Annu. Rev. Biophys. Biomol. Struct. 35 (2006) 225-49 [2] D. V. Kurochkin, S. R. G. Naraharisetty, I. V. Rubtsov, PNAS 104 (2007) 14209-14214

Poster 41

Stimulated Raman Spectroscopy of the Electronic Excited State of

Photoactive Yellow Protein

R. Nakamura1,*, N. Hamada1, Y. Kanematsu1, K. Abe2, and M. Yoshizawa2

1 VBL, CASI, Osaka University, Suita, Japan, *r.nakamura@casi.osaka-u.ac.jp

2 Department of Physics, Tohoku University, Sendai, Japan

Photoactive yellow protein (PYP) from the purple phototrophic bacterium

Ectothiorhodospira halophila is a water soluble and small protein of 14kDa. The

chromophore is p-coumaric acid, which is bound to a cysteine residue by a thioester linkage.

After absorbing a photon, PYP enters the photocycle involving ultrafast trans-cis

isomerization of the chromophore with a 3-ps time constant [1]. In this study, we have studied

the ultrafast structural evolution in the excited state of the chromophore in PYP by

femtosecond stimulated Raman spectroscopy [2]. Figure 1 shows the transient stimulated

Raman spectra in the 600 – 1700 cm1 window at selected time delays after photo excitation.

The stimulated Raman spectrum of the ground state is also shown, which exhibits vibrational

features related to coupled C=C and C-C stretching modes

in the 1450 – 1600 cm1 region, coupled C=C (or C-C)

stretching and in-plane CH rocking modes in the 1100 –

1350 cm1 region, and skeleton or out-of-plane vibrational

modes in the region below 1000 cm1 [3]. The transient

Raman spectrum consists of the dispersive-like lineshape

of the ground state spectrum as indicated by dotted lines

and several new bands in the lower frequency region than

1200 cm1, which decay on a timescale of picoseconds.

References:

[1] K. Heyne, O.F. Mohammed, A. Usman, J. Dreyer, E.T.J. Nibbering, M.A. Cusanovich, J.

Am. Chem. Soc. 127 (2005) 18100.

[2] M. Yoshizawa, H. Aoki, H. Hashimoto, Phys. Rev. B 63 (2001) 180301.

[3] M. Unno, M. Kumauchi, F. Tokunaga, S. Yamauchi, J. Phys. Chem. B 111 (2007) 2719.

Poster 42

Fig. 1: Stimulated Raman signals on the anti-Stokes side of PYP measured by using 460-nm pump and 520-nm Raman pump.

1000 1500

-2.0 ps

0.2 ps

1.0 ps

5.0 ps

Raman Shift (cm-1)

20 ps

GourndState

Picosecond Iron Motion Triggered by Nitric Oxide Binding to Hemoglobin

Sergei G Kruglik1, Byung-Kuk Yoo2, Isabelle Lamarre2, Jean-Louis Martin2, Michel Negrerie2

1Laboratoire Acides Nucléiques et Biophotonique, Univ. Pierre & Marie Curie, Paris, France 2Laboratoire d'Optique et Biosciences, INSERM, Ecole Polytechnique, Palaiseau, France

michel.negrerie@polytechnique.fr

We measured the ultrafast movement of the heme iron induced by nitric oxide (NO)

binding to hemoglobin (Hb) by probing the picosecond kinetics of the vibrational Fe-His

stretching mode (220 cm-1) intensity and that of the absorption band III (760 nm) after NO

photodissociation from Hb. We compared their evolution to that of Soret band (420 nm) and

Q- electronic absorption band (700 nm) and with intensity decay of the Raman 4 mode (1354

cm-1) measured with picosecond resolution in resonance conditions [1]. Both Fe-His stretching

and Band III intensities have been theoretically hypothesized to depend upon the position of

the ferrous iron with respect to the heme plane [2, 3]. We measured the time constants of band

III intensity kinetics induced by NO rebinding after photodissociation (18 ps for Hb and 27.5

ps for Mb), which are different from those of Soret and Q-band, but are in close agreement

with the values obtained by probing the Fe-His stretching intensity (15 ps for Hb and 30 ps for

Mb) [4]. These results confirm that NO can bind to a domed heme [5]. Furthermore, the

kinetics of the spectral shift of band III (11 ps for Hb and 15 ps for Mb) follow NO rebinding

(10.8 ps for Hb and 13 ps for Mb) and not those of band III intensity. We confirmed the

theoretical calculations showing the dependence of band III intensity upon the heme iron

position [2]. Remarkably, we observed a much larger band III spectral shift associated with

NO rebinding to Hb (145 cm-1) than to Mb (78 cm-1). We attributed this difference to larger

structural changes associated with the allosteric transition in the tetrameric Hb.

References:

[1] Kruglik, S. G.; Lambry, J.-C.; Martin, J.-L.; Vos, M. H.; Negrerie, M. J. Raman Spectrosc. (2010)

DOI: 10.1002/jrs.2685.

[2] Stavrov, S. S. Biophys. J. 6 (1993) 1950.

[3] Stavrov, S. S. Chem. Phys. 271 (2001) 145.

[4] Kruglik, S. G.; Yoo, B.-K.; Franzen, S.; Vos, M. H.; Martin, J.-L.; Negrerie, M. Proc. Natl. Acad.

Sci. USA. 107 (2010) 13678.

[5] Ionascu D.; Gruia, F.; Ye, X.; Yu, A. C.; Rosca, F.; Beck, C.; Demidov, A.; Olson, J. S.;

Champion, P. M. J. Am. Chem. Soc. 127 (2005) 16921.

Poster 43

Time-resolved CARS spectral imaging using a nanosecond white-light laser

source

Masanari OKUNO, Hideaki KANO, and Hiro-o HAMAGUCHI

Department of Chemistry, School of Science, The University of Tokyo,

mokuno@chem.s.u-tokyo.ac.jp

Coherent anti-Stokes Raman scattering (CARS) microscopy has been applied widely to

cell and tissue imaging ex and in vivo [1]. CARS microscopy, however, provides only a

monochromatic image using a single vibrational frequency such as CH2 stretch vibrational

mode. In order to obtain full spectral information on vibrational modes, we used a new light

source, nanosecond supercontinuum or white-light laser, which facilitated ultra-broadband

(>3000cm-1) multiplex CARS microspectroscopy. Owing to the narrow spectral bandwidth of

the pump/probe laser in the CARS process, the vibrationally resonant CARS imaging in the

fingerprint region is performed with high

molecular specificity. Figure 1 shows the

real-time CARS imaging of a single living

yeast cell. “Molecular fingerprinting”

inside of a living cell is demonstrated for

the first time [2]. The maximum entropy

method allows us to obtain Im[(3)]

spectra and image, whose intensities are

proportional to molecular concentration.

In the time course shown in Fig. 1, CARS

images show unique mode-dependent

dynamics. It is caused by the cell-death

process through the laser irradiation.

References:

[1] C. L. Evans, X. S. Xie, Annu. Rev.

Anal. Chem. 1 (2008) 883.

[2] M. Okuno, H. Kano, P. Leproux, V. Couderc, J. Day, M. Bonn, and H. Hamaguchi,

Angew. Chem. Int. Ed. 49 (2010) 6773.

Poster 44

Figure 1 Time-resolved CARS images. The scale bar corresponds to 5 m. The red frame on the right contains CARS images at 1160 cm-1 from 19 to 21 min. Each image is measured every 12 seconds.

Divide and conquer – distinguishing between fluxionality and vibrational

energy transfer in Fe(CO)4(olefin) complexes

M.R. Panman1, A.C. Newton, J. Vos, V. Bocokic, J. Reek, S. Woutersen

Van 't Hoff Institute for Molecular Sciences, University of Amsterdam,

Science Park 904, 1098 XH Amsterdam, The Netherlands; e-mail: 1m.r.panman@uva.nl

Two-dimensional infrared spectroscopy (2D-IR) can be used to observe ultrafast dynamics in

transition-metal complexes, in particular vibrational energy transfer [1] and the fast

rearrangement of ligands between axial and equatorial positions (fluxionality) [2].

Fe(CO)4(cinnamic acid), see Figure 1A, has symmetric and antisymmetric axial (νas and νaa)

CO-stretching modes that are spectrally well separated from each other and the equatorial (νe)

modes [3]. It is therefore possible to determine separately the contributions from vibrational

energy transfer and fluxionality to the observed cross-peak exchange dynamics. We find that

the vibrational redistribution from the νe to both the νa modes occurs at the same rate. This is

conclusive evidence that the exchange is caused by fluxionality and not vibrational energy

transfer, since the rate of the latter varies with the donor-acceptor coupling and energy

difference, and would therefore be different for the νe → νas and νe → νaa mode pairs.

Figure 2: (A) Fe(CO)4cinnamic acid. 2D-IR spectra at 0.7 ps (B) and 10 ps (C) and linear infrared spectra of Fe(CO)4(cinnamic acid).

References:

[1] Golonzka O., et al., Chem. Phys. A, 15 (2001) 10814

[2] Cahoon J.F., Sawyer K.R., Schlegel J.P. and Harris C.B., Science 319 (2008) 1820.

[3] Darensbourg D.J., Nelson H.H., and Hyde C.L., Inorg. Chem. 13 (1974) 2135

Poster 45

0.00 0.05 0.10 0.15 0.200.0

0.2

0.4

0.6

0.8

3300 3500

3300

3500

1 (cm-1)

3

(cm

-1)

TBA, anisotropy TMAO, anisotropy

Theory

Fra

ctio

n o

f slo

wly

reo

rient

ing

wa

ter

TBA/TMAO molar concentration

0.0

0.2

0.4

0.6

TBA, 2D IR TMAO, 2D IR

Fra

ctio

n o

f wat

er w

ith s

low

spe

ctra

l diff

usio

n

Figure 1. Fractions of water with slow spectral (circles) and orientational (rhombs) dynamics as a function of solute (TBA or TMAO) concentration. Solid curves are calculated on basis of the chemical equilibrium model that excellently describes TMAO solvation (blue) but fails for TBA (pink) due to TBA aggregation. The inset shows a typical example of the 2D IR spectrum of TBA at a waiting time of 0.1 ps. Note the diagonal elongation of the 2D spectrum that is indicative of slow spectral dynamics.

Aggregation of Amphiphilic Molecules in Aqueous Solutions

Vlad G. Pavelyev1, Artem A. Bakulin1, Christian Petersen2, Huib J. Bakker2, Paul H.M. van Loosdrecht1, Maxim S. Pshenichnikov1

1 Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG

Groningen, The Netherlands, m.s.pchenitchnikov@rug.nl 2 FOM Institute for Atomic and Molecular Physics, Science Park 113, Amsterdam, The Netherlands,

h.bakker@amolf.nl

Hydration effect of amphiphilic solutes is one of the focusing points for many research areas

ranging from material science to biology, and as such has been studied extensively [1]. An

intriguing property of amphiphilic molecules is that they can form aggregates in aqueous

solution due to the interplay between hydrophilic and hydrophobic interactions. Despite the

fact that these interactions play a prominent role in biological processes such as protein

folding and the formation of bilipid membranes, there is no clear understanding of the

underlying structure and dynamics of such mixtures.

Here we study aggregation of two amphiphilic molecules, tertiary butyl alcohol (TBA)

and trimethylamine-N-oxide (TMAO) in aqueous solutions, with fs 2D IR and polarization-

resolved pump-probe spectroscopy [2].

Both the spectral and orientational

dynamics are observed to exhibit a

bimodal behavior: a part of the water

molecules shows spectral and

orientational dynamics quite similar to

bulk liquid water, while another part

displays much slower dynamics. The

fraction of the “slow” water (Fig.1) for

TMAO solutions can be excellently

described by a chemical equilibrium

model indicating the competition of the

solvation sites for solvating water

molecule. However, for TBA solutions

the saturation begins earlier and does not

reach a unity level which suggests that all

additional TBA molecules are embedded

by other TBA molecules, i.e. incorporated in TBA aggregates. References:

[1] D. Chandler, Nature, 437, 640 (2005). [2] C. Petersen et al., J.Chem.Phys. 133 164514 (2010).

Poster 46

Ultrafast 3D IR-Raman pump-probe spectroscopy to monitor

spatially-resolved energy transfer in nitrobenzene*

Brandt Pein1, Yuanxi Fu2, Dana Dlott3

1 School of Chemical Sciences University of Illinois at Urbana-Champaign,

Pein1@illinois.edu 2 School of Chemical Sciences University of Illinois at Urbana-Champaign, Fu5@illinois.edu

3 School of Chemical Sciences University of Illinois at Urbana-Champaign,

Dlott@illinois.edu

In this work, ultrafast three-dimensional IR-Raman pump-probe spectroscopy is used

to observe how vibrational energy transfers from one moiety of a molecule to another. In this

particular study, liquid state nitrobenzene is excited with ultrashort IR pulses that

predominately populate excitations of the nitro or phenyl group which are then observed in

real time as the energy is exchanged from one group to the other. To determine the IR regions

of nitro or phenyl excitation, the populations at 1 picosecond after the IR pulse are observed

over a dense range of pump frequencies from 3500 cm-1 to 2500 cm-1. The transient spectra

from pump-probe delays of -3 to 100 picoseconds demonstrate that nitrobenzene restricts

energy transfer to the phenyl modes upon excitation of the nitro moiety while energy is free to

transfer to the nitro modes upon excitation of the phenyl moiety. This behavior is remarkable

as other mono-substituted benzenes have shown no such energy restriction to a specific

mode1,2. This three-dimensional strategy is quite general and can be applied to an array of

systems. *The research described in this study is based on work supported by the National Science

Foundation under award DMR-09-55259 and the US Air Force Office of Scientific Research

under award number FA9550-09-1-0163.

References:

[1] Seong, N.; Fang, Y.; Dlott, D., J. Phys. Chem. A. 113 (2009) 1445.

[2] Pein, B.; Seong, N.; Dlott, D., J. Phys. Chem. A. 114 (2010) 10500.

Poster 47

2D IR Spectroscopy of Nucleic Acid Bases

Chunte Sam Peng, Kevin C. Jones, and Andrei Tokmakoff

Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139

E-mail: sampeng@mit.edu

DNA can adopt a wide variety of conformations. These sequence-dependent structural

variations have important roles in their biological functions, such as DNA packaging,

replication, transcription, and protein recognition. Vibrational spectroscopy is known to

reflect DNA conformation, and basic assignments of resonances in the vibrational IR and

Raman spectra of nucleic acids have existed for decades. However, models that describe the

vibrational spectroscopy of nucleic acid secondary structure are not developed. Traditional

spectral assignments of base vibrations are based on simple local vibrational mode basis such

as C=O, C=C, and C=N double bond stretches, although computational studies describe

highly delocalized DNA vibrations1. Heterodyne-detected 2D IR spectroscopy experiments

have been performed to obtain the strengths of vibrational couplings in double stranded DNA

helix, both on the carbonyl stretches2 and NH2 stretches3.

We acquired polarization dependent 2D IR spectra of the purine and pyrimadine base

vibrations of five nucleotide monophosphates (NMPs) as the building blocks for developing a

model of DNA and RNA vibrational spectroscopy. The distinctive cross-peaks between the

vibrational modes of NMPs, such as ring vibrations and C=O stretches, indicate that these

vibrational modes are strongly coupled anharmonic oscillators. We have characterized the

eigenstate energies, vibrational anharmonicities, transition dipole strengths, and their relative

orientations through the analysis and modeling of the experimental 2D IR spectra. To

interpret the molecular origins of these vibrational modes, we also performed density

functional theory (DFT) calculations and found that multiple ring vibrations are strongly

coupled and delocalized over the purine/ pyrimidine rings.

Figure: Polarization dependent 2D IR spectra of adenine 5’-monophosphate (AMP) in D2O in the DNA fingerprint spectral region. The left and right columns display the ZZZZ and ZZYY spectra, respectively. The top row is the experimental data and the bottom row is obtained from model calculation using coupled anharmonic oscillators. From our analysis, the two vibrational modes have transition dipole moments that are perpendicular to one another.

References: [1] Lee, C.; Park, K.-H.; Cho, M. J. Chem. Phys. 125 (2006), 114508. [2] Krummel, A. T.; Mukherjee, P.; Zanni, M. T. J. Phys. Chem. B. 107(2003), 9165. [3] Yang, M., et. al. J. Phys. Chem. B (2011), ASAP.

Poster 48

Two Dimensional Infrared Spectroscopy of Ice Ih

Fivos Perakis and Peter Hamm

Physikalisch-Chemisches Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057

Zürich, Switzerland, phamm@pci.uzh.ch

Proton disorder is an intriguing characteristic of many ice forms, due to its possible

implication to phonon and exciton dynamics of the hydrogen bonded crystals [1]. With 2D IR

spectroscopy of the OD stretch we address the aforementioned problem experimentally,

investigating the isotope diluted (HOD in H2O) and neat (D2O) ice Ih at T=80 K. For the

isotope diluted case the main spectral features observed are the extremely broad 1-2 excited

state transition, much broader than the corresponding 0-1 ground state transition in agreement

with previous studies [2], as well as the presence of quantum beats. Complementary

simulations in the framework of the Lippincott-Schroeder model [3] qualitatively reproduce

our experimental observations. Analysis of the neat 2D spectra reveals a truly exotic lineshape

with a large distribution of beating frequencies. We conclude that these features reflect the

complex interplay of the underlying processes, as vibrational exciton coupling, phonon

contributions as well as the impact of Fermi resonances.

References:

[1] Li F., Skinner J. L., J. Chem. Phys. 133 (2010) 244504.

[2] Dokter A. M., Bakker H. J., J. Chem. Phys. 128 (2008) 024502.

[3] Lippincott E.R., Schroeder R., J. Chem. Phys. 23 (1955) 1099.

Poster 49

230

0 22

00

240

0 26

00

2300 2200 2400 2500

250

0

2300 2200 2400 2500

(OD of 100% D2O) (OD of 5% HOD in H2O)

p

um

p(

cm-1

)

probe(cm-1)

Neat Isotope diluted

probe(cm-1)

Ultrafast vibrational energy relaxation of the water bridge

Lukasz Piatkowski1, Adam D. Wexler2, Elmar C. Fuchs2, Hinco Schoenmaker1, Huib J.

Bakker1

1 FOM Institute for Atomic and Molecular Physics – AMOLF, Science Park 104, 1098 XG

Amsterdam, The Netherlands

2 Wetsus—Centre of Excellence for Sustainable Water Technology, Agora 1, Leeuwarden, The Netherlands

We report on a femtosecond, mid-infrared spectroscopic study of water constituting the so-

called water bridge. This phenomenon occurs when a high electric potential (~kV) difference

is applied between two beakers filled with chemically pure water. Induced by the electric

field, water creeps towards the edges of the beakers, thereby producing a suspended string of

water in between them.

The water bridge phenomenon has been reported first

in 1893 by William Armstrong. Since then scientists

studied similar effects, like electrowetting or the Sumoto

effect, but the water bridge itself had been studied very

little. Several recent publications have succesfully

addressed the macroscopic physical mechanism behind

the formation of the water bridge [1]. An interesting

question is whether the water bridge differs from

ordinary bulk water on the molecular scale or only represents a macroscopic space charge

effect.

Here we present a study of the vibrational energy relaxation dynamics of water molecules in

the water bridge. These energy dynamics are directly connected to the molecular-scale

properties of the hydrogen-bond network of water and as such form a useful probe of the

properties of this network

We observed that the formation of the water bridge has a pronounced effect on the rate of

energy transfer between the molecular vibrations of water. The vibrational relaxation time

constant of the OH stretch vibration of an isotopically diluted water bridge (~0.5% HDO in

D2O) is significantly shorter (600±30 fs) than for HDO molecules in a bulk HDO:D2O

solution (740±30 fs). Interestingly, the thermalization dynamics following the vibrational

relaxation of the OH stretch vibration are slower for the water bridge (1.5±0.4 ps) than for a

bulk HDO:D2O solution (250±90 fs). Our results demonstrate that the formation of a water

bridge is associated with a change of the properties of water on the molecular scale, in

particular of the low-frequency degrees of freedom.

References:

[1] Marin, A. G.; Lohse, D., Phys. Fluids 22 (2010) 122104.

Poster 50

Snapshots of ligand-hemeprotein interaction taken with sub-picosecond

time resolution

E. Pontecorvo1, S.M. Kapetanaki1, M. Badioli1, D. Brida2, M. Marangoni2, G. Cerullo2 and

T. Scopigno1 1 Dipartimento di Fisica, Universita’ Roma “Sapienza”, Roma, Italy

2 IFN-CNR and Dipartimento di Fisica, Politecnico di Milano, Milano, Italy

The ability to create stable femtosecond pulses of laser light has given chemists access to the

reaction and structural dynamics of a host of biomolecules that were formerly off-limits. The

real challenge is studying biomolecular structure in the 10-femtosecond to 1-picosecond time

domain, the intrinsic time over which chemical reactions occur.

Femtosecond Stimulated Raman Spectroscopy (FSRS) is a new powerful method for studying

bio-chemical reaction dynamics. By recording stimulated Raman scattering spectra of a

molecule as a function of the time delay with respect to an ultrashort pulse triggering a

photochemical process, it allows to acquire snapshots of its vibrational structure with an

unprecedented combination of temporal and spectral resolution. It has been already

successfully applied to the study of a number of primary photochemical reactions. FSRS

requires the generation of three synchronized pulses: a narrowband picosecond pulse (the

Raman pump) and two broadband femtosecond pulses, the actinic pump and the Raman

probe. The easiest implementation of FSRS synthesizes the Raman pump by linear spectral

filtering the pulses from Ti:Sapphire laser. The 800-nm wavelength however, is not ideal for

several applications and in particular it does not allow exploiting resonance enhancement of

the Raman response in proteins.

Building on a femtosecond source, we recently introduced a simple technique -that we called

“spectral compression”- for the efficient synthesis of multi-μJ, picosecond pulses tunable in

the range 330 to 510 nm. The characteristics of these pulses make them ideally suited as

Raman pump for FSRS spectroscopy, in particular for many biomolecules displaying

resonances in the UV.

We will present here snapshots of heme-ligand interaction in horse heart Myoglobin as

determined by means of FSRS. Spectral resolution is sufficient to unravel different ligation

states of the heme, while time resolution is ~40fs, enough to track the sub-ps dynamics of the

photolyzed system.

Poster 51

Phase-sensitive sum-frequency generation spectroscopy achieved by

heterodyne detection at aqueous interfaces

Ruben Pool1, Jan Versluis1, Ellen Backus1, Mischa Bonn1

1 FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands

(pool@amolf.nl)

Throughout the last fifteen years, sum-frequency generation (SFG) spectroscopy has

become an established tool in studying aqueous interfaces. By probing vibrational modes of

water and, e.g., surfactants through their second-order susceptibility χ(2), the background-free

and surface-specific spectrum of a layer of a thickness of just a few molecules can be

acquired. One of the drawback of conventional SFG is the fact that the intensity spectra

reflect | χ(2)|2, so that the information of the sign of χ(2), which reflects the orientation of the

interfacial molecules, is lost

The latest development in SFG spectroscopy is the application of a heterodyne detection

scheme, in which a non-resonant local oscillator is mixed with the SFG signal. By introducing

a delay between the signal of the sample and that of the local oscillator, the linear cross terms

can be extracted from the resulting detected signal. This technique allows one to retrieve the

phase information, thus allowing heterodyne detection to find the absolute orientation of

water and surfactants at the interface. On the other hand, the analysis of heterodyne-detected

data is not as straightforward as in the homodyne case due to the necessity of applying phase

corrections to the complex spectra because of the reflection coefficients of sample and local

oscillator. We discuss the potential and limitations of heterodyne-detected SFG spectroscopy

and compare the approach to other phase retrieval methods based on homodyne detection.

Comparison of the squared magnitude of the heterodyne SFG spectrum of the phospholipid

DPPC to the homodyne spectrum (left), and depiction of its complex components (right)

Poster 52

SFG intensity (a.u.)

34003200 30002800

IR frequency (cm-1)

HomodyneHeterodyne

SFG intensity (a.u.)

3400 3200 30002800

Heterodyne real

Heterodyne imaginary

IR frequency (cm-1)

Photocatalytic Generation of Hydrogen in Water as Solvent Spectroscopic

Insights into the Mechanism

Alexander Rodenberg1, Miguel Guttentag2, Benjamin Probst2, Roger Alberto2, Peter Hamm1

1 Institute of Physical Chemistry, University of Zurich, a.rodenberg@pci.uzh.ch

2 Institute of Inorganic Chemistry, University of Zurich

We use time resolved IR spectroscopy from pico- to milliseconds to elucidate mechanism and

kinetics of the photocatalytic hydrogen production from water with homogeneous transition

metal systems, namely the combination of photosensitizers (PS) based on the fac-tricarbonyl-

rhenium(I)-moiety with cobaloxime-type water reduction catalysts (WRC) in pure water as

solvent. The catalytic system is completed by sacrificial electron donors as triethanolamine

(TEOA) or ascorbate (Hasc−). With the latter turnover numbers as high as ~3000 H/Re and

~110 H2/Co catching up with the best reported values in dimethylformamide (DMF) as

solvent were achieved. This constitutes a major step towards a full water splitting system

since up to now the oxidation of water to dioxygen exclusively works in this solvent.

It was found that for the PS in water catalysis follows the same mechanism as in DMF, i.e.

reductive quenching of the 3MLCT state of the PS by the sacrificial electron donor followed

by electron transfer from PS− to the WRC. With the help of time resolved IR spectroscopy we

could unambiguously assign the above-mentioned reaction steps including kinetics and

quantum yields of quenching / cage-escape and electron transfers. Both processes happen at

close to diffusion controlled rates (~108-109 M−1s−1), while in water cage escape yields

(TEOA: ~0.75, Hasc−: ~0.6) are significantly increased as compared to DMF (TEOA: ~0.3).

Long term stability of the catalytic system is limited by the decomposition of the WRC and in

case of Hasc− also by the consumption of the latter, since electron back transfer to its oxidised

form dehydroascorbic acid takes place. This reversibility opens up the possibility to use this

redox couple as an electron shuttle between water reduction and an oxidative counterpart.

References:

[1] B. Probst, A. Rodenberg, M. Guttentag, P. Hamm, R. Alberto, Inorg. Chem. 2010, 49

(14), 6453-6460.

[2] B. Probst, M. Guttentag, A. Rodenberg, P. Hamm, R. Alberto, Inorg. Chem. 2011, 50 (8),

3404-3412.

Poster 53

Solvent and Conformation Dependence of Amide I Vibrations in Proteins

with Proline

Santanu Roy, Jasper Knoester and Thomas la Cour Jansen

Theory of Condensed Matter

Zernike Institute for Advanced Materials, University of Groningen, The Netherlands

Infrared linear and 2D spectroscopy of the amide I (CO stretch) region are excellent tools

to investigate protein structure and dynamics. This is because the frequency of and the

coupling between the amide carbonyls along the protein backbone depends on the

surrounding solvent and the conformation. In order to understand the experimental spectra

modeling of the amide I band is a necessity. There are existing models to extract frequencies

and couplings between the amide I oscillators [1, 2]. These models, however, only apply to

secondary amides, and thus not to proline, which is a tertiary amide. Proline is an important

amino-acid residue frequently found in β-turns and in high abundance in proteins as elastine

and collagen. Hence, we require a new map for proline. Here, we construct the electrostatic

and dihedral maps accounting for solvent and conformation effects on frequency and coupling

for the proline unit. We validate the mappings on acetyl proline and PG12 comparing with

experimental results [3, 4]. Apart from a systematic frequency shift the agreement of the

lineshape between experiment and simulation is excellent.

References:

[1] Jansen et al., J. Chem. Phys. 124, 044502, (2006).

[2] Jansen et al., J. Chem. Phys. 125, 044312, (2006).

[3] Unpublished data for acetyle proline from the Tokmakoff group at MIT

[4] Smith et al., Angew. Chem. Int. Ed. 46, 7984 (2004)

Poster 54

Ground State Proton Transfer Rate Measurement by 2D IR Spectroscopy

William T. Rock

Department of Chemistry and Optical Science and Technology Center, University of Iowa,

Iowa City, Iowa 52242

Proton transfer reactions play an integral role in many important chemical processes

including acid-base reactions, enzyme catalysis, and biological energy

transduction.1 Therefore, a thorough understanding of the kinetics of proton transfer

reactions is paramount to the study of these important systems. There are many competing

theoretical models for calculating proton transfer rates, and, although they have all been

applied to the same phenol/triethylamine model, the predicted reaction rates differ by four

orders of magnitude.2-7 Unfortunately, there is no experimental benchmark for the rate of this

reaction because of the experimental challenges associated with measuring the rates of

ground-state proton transfers in solution. We report a 2D IR chemical exchange study of 2-

cyanophenol/triethylamine complexes in dichloromethane. The CN stretching transition

serves as an indirect reporter of the protonation state of the phenol. Thus, the chemical

exchange experiments allow us to determine the kinetics of the proton-transfer equilibrium in

these complexes. The ability to directly measure the kinetics of the ground electronic state

proton transfer in solution provides an opportunity to characterize the interactions that govern

proton transfer reaction rates.

References:

[1] K. Ando and J.T. Hynes, Adv. Chem. Phys. 110 (1999) 381. [2] H. Azzouz and D. Borgis, J. Chem. Phys. 98 (1993) 7361. [3] S. Hammes-Schiffer and J. C. Tully, J. Chem. Phys. 101 (1994) 4657. [4] D. Antoniou and S. D. Schwartz, J. Chem. Phys. 110 (1999) 7359. [5] R. P. McRae, G. K. Schenter, B. C. Garrett, Z. Svetlicic, and D. G. Truhlar, J. Chem. Phys. 115 (2001) 8460. [6] S. Y. Kim and S. Hammes-Schiffer, J. Chem. Phys. 119 (2003) 4389. [7] T. Yamamoto andW. H. Miller, J. Chem. Phys. 122 (2005) 044106.

Poster 55

Ultrafast hole transfer dynamics in polymer:fullerene blends

Almis Serbenta, Vlad G. Pavelyev, Jan C. Hummelen, Paul H. M. van Loosdrecht,

Maxim S. Pshenichnikov

Zernike Institute for Advanced Materials, University of Groningen, The Netherlands

e-mail: a.serbenta@rug.nl

Current state-of-the-art organic photovoltaic devices are based on polymer:fullerene bulk

heterojunctions [1]. In the conventional polymer:[60]PCBM blends when exposed to the

sunlight the major absorption contribution originates from the polymer with a subsequent

electron transfer to the fullerene. However, with the recent introduction of [70]PCBM

fullerene the absorption of the fullerene itself becomes so substantial that it becomes

important to understand the creation of an exciton on the PCBM molecule followed by its

dissociation into charges through the so-called hole-transfer (HT) process. Despite its obvious

fundamental importance and practical interest to solar cell design, HT dynamics have received

surprisingly little attention so far [2].

We investigate the ultrafast hole

transfer from [70]PCBM to different

polymers in polymer:[70]PCBM

blends using visible pump – IR probe

spectroscopy using selective

[70]PCBM excitation, while probing

the presence of charges through

detection of the low-energy polymer

polaron band at 3 m. Tuning the

fullerene concentration allows us to

vary the fullerene contribution to the

overall absorption efficiency, and

address the morphology issue. We

found that in the P3HT:[70]PCBM blends, the hole transfer time is noticeably longer than in

MDMO-PPV:[60]PCBM blends (Fig.1). Also, in all blends the charge generation at the

ultrafast scale efficiency sharply decreases with the increase of fullerene concentration which

indicates a limited exciton diffusion length in the fullerene domain.

References:

[1] J. Peet et al., ACR 42 (2009) 1700

[2] A. A. Bakulin et al., Adv. Funct. Mater. 20 (2010) 1653

Poster 56

0 20 40 60 800

20

40

60

80

100

120

140

-0.2 0.0 0.2 0.4 0.6 0.80

17

PPV:[70]PCBM

PPV:[60]PCBM2

P3HT:[70]PCBM

Del

ay

(fs)

PCBM concentration (%)

Delay (ps)

75% [70]PCBMApparatus resp.

-T

/T (

x 10

3)

Fig. 1 Hole transfer delay as a function of PCBM content in different polymer-fullerene blends. The inset shows an example of the photoinduced absorption transient from which the delay is inferred.

Vibrational Dynamics of [RuCl5(NO)]2- in Aqueous Solution Studied by

Nonlinear Infrared Spectroscopy

Kyoko Aikawa1, Junpei Tayama2, Motohiro Banno2, Kaoru Ohta2,3, Shinji Saito4, and

Keisuke Tominaga1,2

1Graduate School of Science, Kobe University, Kobe, Japan 2Molecular Photoscience Research Center, Kobe University, Kobe, Japan

3PRESTO, JST, Kobe, Japan 4Institute for Molecular Science, Okazaki, Japan

e-mail: tominaga@kobe-u.ac.jp

In aqueous solution, molecular dynamics is charactarized by a wide time scale ranging

from a few tens of femtoseconds to a few picoseconds. Nonlinear optical spectroscopy has

been applied to investigation these dynamics quantitatively. In this study, we examine

vibrational dynamics of the NO stretching mode of [RuCl5(NO)]2- (NR) in light and heavy

water. We performed IR pump-probe and 2D IR spectroscopic methods to discuss the

vibrational energy relaxation (VER), the rotational relaxation, and the frequency fluctuation.

The VER time constant of the NO stretching mode of NR at 293 K is 7.7 and 30.8 ps in

H2O and D2O, respectively. These values decrease about 10% in both solvents as temperature

increase. The rotational relaxation time constant of the NO stretching mode at 293 K is 20 and

30 ps in H2O and D2O, respectively. These values decrease about 50% in both solvents as

temperature increases.

The obtained 2D-IR spectrum is shown in Fig. 1. The

center line slope (CLS) of the 2D IR signal is plotted

against the population time T. The CLS is directly

proportional to the frequency-frequency correlation

function. The time dependence of the CLS is well fitted by

a double-exponential function with time constants of 0.9

and 6.6 ps in H2O, and 0.8 and 11 ps in D2O. By choosing

NR as a probe molecule, we have conceivably observed the

slow dynamics with the time constant more than a few

picoseconds.

Poster 57

1900

1880

1860

1840

3

/ cm

-1

19001860

1 / cm-1

(a)

Fig. 1. The 2D-IR spectra of NR in H2O at T = 200 fs.

Frequency Dependence of Vibrational Energy Relaxation and Spectral

Diffusion of Pyrrole-base Complexes in Solution

Sayuri Yamaguchi1, Motohiro Banno2, Kaoru Ohta2, and Keisuke Tominaga1,2

1 Graduate School of Science, Kobe University, Nada, Kobe, Japan.

2 Molecular Photoscience Research Center, Nada, Kobe, Japan.

e-mail: tominaga@kobe-u.ac.jp

Vibrational dynamics of the NH stretching mode of pyrrole-base complexes in carbon

tetrachloride (CCl4) have been studied by sub-picosecond infrared pump-probe (PP)

spectroscopy. Previously, Grubbs et al. have reported that the vibrational energy relaxation

becomes faster as hydrogen bond becomes stronger for several pyrrole-base complexes [1].

We here discuss frequency dependence of the PP signal decay with consideration of spectral

diffusion. As shown in Figure 1, the decay time of the PP signal for the NH stretching mode

of pyrrole-diethylether in CCl4 shows frequency dependence in the complex band around

3350 cm-1, and the dependence was observed for the other pyrrole-base complexes as well.

The observed frequency dependence is explained by considering both frequency dependence

of the vibrational population relaxation and spectral diffusion, and we simulated the

experimental observation by modified Smoluchowski equation.

Reference: [1] Grubbs, W. T.; Dougherty, T. P.; Heilweil, E. J. J. Phys. Chem. 99 (1995)

10716.

Poster 58

Figure 1. Frequency dependene of the decay time obtained from the bleaching and transient absorption signals for pyrrole-diethylether in CCl4 with the absorption spectrum.

7

6

5

4

3

2

1/k r /

ps

3400330032003100

wavenumber / cm-1

1.0

0.5

0.0

abs.v=0→v=1

v=1→v=2

Structural determination of the protein human -synuclein associated with

a lipid bilayer using two-dimensional IR spectroscopy

David R. Skoff1, Martin T. Zanni2

1University of Wisconsin-Madison, dskoff@chem.wisc.edu 2University of Wisconsin-Madison, zanni@chem.wisc.edu

Recently, infrared spectroscopy combined with residue specific labeling has been used

for protein structure determination in an analogous fashion to electron paramagnetic

resonance spectroscopy combined with site-directed spin labeling. Various infrared probes

including backbone isotope labels (13C=18O), thiocyanate labels, and azide labels, have been

used to report on local environments of a specific residue. However, pitfalls due to weak

infrared absorption or absorbance in crowded spectral regions have left researchers searching

for a more versatile probe. Here we report on developments of a new infrared probe,

tricarbonyl(cyclopentadienyl) rhenium (η5-C5H5)Re(CO)3, which is shown to be an order of

magnitude more absorbent than other IR labels and in a spectrally free region. We also

present its application to the structural determination of human α-synuclein. Human α-

synuclein is a 140 amino acid protein that aggregates into insoluble fibrils in humans with

Parkinson’s disease. In its membrane-bound form an asymmetric environment surrounds the

protein since one face of the -helix is toward the membrane surface and the other is toward

water. This asymmetry allows structure and orientation to be determined by measuring which

residues are water or lipid associated. By considering 1DIR and 2DIR observables of the new

IR probe such as center peak frequency, inhomogeneous line width, and nodal tilt angle, we

search for the most sensitive observable to differentiate water exposed and water excluded

environments.

Poster 59

Spheres and tubes: the influence of geometry on the structure and

dynamics of nano-confined water

Tibert H. van der Loop1, Wiebke Sager2, and Sander Woutersen1

1Van ’t Hoff Institute for Molecular Sciences, University of Amsterdam, Sciencepark 904,

1098 XH Amsterdam, The Netherlands; e-mail: T.H.vanderloop@uva.nl

2 Institute of Solid State Research (IFF), Forschunszentrum Jülich,

Postfach 1913, 52425 Jülich, Germany

In the living cell, water is often found in nano-confined spaces, for instance between lipid

membranes or in the channels of protein pumps. These nanometer-size pockets of water have

been found to behave very differently from bulk water. The effect of nano-confinement on the

structure and dynamics of water has been studied previously for spherical geometries[1,2].

Here, we investigate the effect of the shape of the nanometer-sized volume on the dynamics

of water. In particular, we use femtosecond time-resolved vibrational spectroscopy on the

OD-stretch mode of HDO:H2O to investigate the reorientational dynamics of water in reverse

micelles of tubular and spherical shape, and different sizes. The geometries were verified with

small-angle neutron scattering. Preliminary results (see Figure) show that in spheres and tubes

with the same water:surfactant ratio w the reorientational dynamics are significantly different.

Anistropy spheres and tubes ( wo)

References:

[1] Dokter, A. et. Al. Phys. Rev. Lett. 94 (2005) 178301

[2] Park, S et. al. Phys. Rev. Lett. 112 (2008) 5279

Poster 60

The Effect of Cations on the Anionic Hydration Shell

Sietse T. van der Post1, K.-J. Tielrooij, M. Bonn, Huib J. Bakker

FOM Institute Amolf, Science Park 104, Amsterdam, The Netherlands

Aqueous salt solutions have been studied intensively over the past century due to their

relevance to many systems. It is therefore surprising that still little is known about the exact

nature of ion hydration. We studied the orientational relaxation of the OD stretch vibration in

concentrated solutions of alkali-halide salts in isotopically diluted water (4% D2O in H2O),

using polarization-resolved femtosecond infrared pump-probe spectroscopy (fs-IR). With this

technique we measure the dynamics of the anisotropy of the excitation of the OD stretch

vibration which directly reflects the second-order Legendre polynomial of the orientational

correlation function. We were able to distinguish the anisotropy decay of water molecules

solvating the halide ions from that of bulk water. We observed that the hydroxyl groups of

water molecules that are hydrogen bonded to halide anions reorient on two distinctly different

timescales. The fast component can be assigned to the librational motion of the hydroxyl

group bonded to the anion. The amplitude of this fast component is observed to decrease

when the cation interacts more strongly with water. This notion shows that cations can have a

significant effect on the orientational mobility of water molecules in the hydration shells of

the anions[1].

References:

[1] Tielrooij, K.-J.; Garcia-Araez, N.; Bonn, M.; Bakker, H.J., Science 328 (2010) 1006-1009.

Poster 61

Rearrangements of hydrogen-bonding interactions in the solvation shell of

a photoswitchable catalyst

Luuk van Wilderen1, Manuel Pescher1, Susanne Gruetzner2, Stefan Hecht2, Jens Bredenbeck1

1 Institut für Biophysik, Goethe-Universität, Frankfurt am Main, Germany,

vanwilderen@biophysik.uni-frankfurt.de

2 Humboldt-Universität zu Berlin, Berlin, Germany

The photoswitchable catalyst developed by Stoll et al. [1] allows light-induced change of the

compound’s basicity and hydrogen-bonding affinity. The system’s catalytic activity is

controlled by photoisomerization of its azobenzene moiety that shields the basic active site

from solvent and interaction partners, for instance alcohols. Here, we report FTIR and

ultrafast time-resolved infrared studies of the isomerization process in the presence of an H-

bond donor. Changes in the vibrations of the system between 1000 cm-1 and 3700 cm-1 reflect

photoisomerization of the catalyst as well as changes in its hydrogen-bonding interactions.

Most notably, light activation induces hydrogen-bonding between donor and catalyst, while

reverse switching expels the H-bond donor from the binding site.

N

O

O

N

NR'

R'

R

N R'

R'

N

N

O

O

R

CH3

CH3

CH3

CH3CH3

E-form Z-form

R'=

R=

365 nm

420 nm

Fig. 1. The inactive E-form can photoreversibly form the catalytically active Z-form. The grey

area symbolises the free electron pair forming the active site.

References:

[1] Ragnar S Stoll, Maike V Peters, Andreas Kuhn, Sven Heiles, Richard Goddard, Michael

Bühl, Christina M Thiele, and Stefan Hecht. JACS, 131 (2009) 357–367

Poster 62

Vibrational dynamics in hydrogen-bonded chains

Stephan Knop1, Thomas La Cour Jansen2, Jörg Lindner1, and Peter Vöhringer1

1Institute for Physical and Theoretical Chemistry, University of Bonn, 53115 Bonn, Germany

2Institute for Theoretical Physics and Materials Science Centre, University of Groningen,

Netherlands

p.voehringer@uni-bonn.de

Femtosecond 2DIR spectroscopy was carried out on diastereomeric polyalcohols. These

systems consist of saturated hydrocarbons carrying an alternating methyl-hydroxyl

substitution pattern. Depending upon the stereochemical orientation of their hydroxyl groups,

the polyols are either to form extended quasi-linear chains of hydrogen bonds that are

structurally robust for extended periods of time (all-syn orientation of the OH-groups) or they

can exhibit ultrafast dynamics of hydrogen-bond breakage and formation (all-anti) [1,2]. In

the all-syn case, the OH-stretching vibrations and their transition dipoles are substantially

coupled. As a result, before vibrational relaxation can fully set in, an OH-excitation from an

ultrafast resonant mid-IR pulse is rapidly redistributed among all the hydroxyl-groups

constituting the H-bonded chain. This vibrational redistribution is responsible for an ultrafast

loss of memory regarding the frequency of initial excitation and as a result, a pump-frequency

independent vibrational lifetime is observed. The measured vibrational lifetime represent a

thermal average over the set of four OH-modes regardless of the frequency of excitation. In

contrast, in the all-anti case, the coupling of the OH-groups and their transition dipoles is

much weaker. The OH-excitation remains localized on the initially excited oscillator for the

time scale of vibrational relaxation. A resonant mid-IR pulse is able to selectively excite from

the inhomogeneously broadened resonance a specific sub-ensemble that relaxes with its own

unique lifetime as defined by the sub-ensemble’s instantaneous H-bond geometry. As a result

inhomogeneous relaxation dynamics with a pump-frequency-dependent lifetime are observed.

References:

[1] J. Seehusen, D. Schwarzer, J. Lindner, and P. Vöhringer. Phys. Chem. Chem. Phys. 11,

(2009) 8484.

[2] S. Knop, T. L. C. Jansen, J. Lindner, and P. Vöhringer. Phys. Chem. Chem. Phys. 13,

(2011) 4641.

Poster 63

Ultrafast Investigation of Excited State Dynamics of the Photochromic

Anabaena Sensory Rhodopsin

Amir Wand1, Rinat Rozin2, Tamar Eliash2, Mordechai Sehves2 and Sanford Ruhman1

1 Institute of Chemistry and the Farkas Center for Light-Induced Processes, Hebrew

University of Jerusalem 91904, Israel.. E-mail: amir.wand@mail.huji.ac.il. 2 Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.

Photochemistry of the newly-discovered Anabaena Sensory Rhodopsin (ASR) [1] is

followed using ultrafast pump-probe spectroscopy and impulsive vibrational spectroscopy,

covering a wide probing spectral range (~450-1650 nm). The photochromic ASR has two

active ground state configurations, one all-trans (AT, dark-adapted) and the other 13-cis (13C,

light-adapted), which inter-convert through their light cycles [2]. Studying this unusual retinal

protein thus offers a unique opportunity for investigating how the excited state dynamics of

the retinal, common to this family of photoreceptors, depend on the initial configuration of the

critical C13=C14 bond, and possibly to clarify the extreme dynamic differences between

photochemistry of bacterial retinal proteins, and those characteristic of the visual pigments.

Our results reveal different dynamics for the different forms (AT vs. 13C), assigning faster

lifetimes for the 13C form, in agreement to the known ultrafast kinetics of the visual pigments

(Rhodopsin) as compared to the archaeal retinal proteins (Bacteriorhodopsin, etc.). The ASR

presents bi-exponential excited state dynamics, similar to other RPs, and characteristic spectra

of the intermediate states are extracted with global kinetic analysis. These reveal considerable

differences in the absorptive and emissive bands of both forms (spectral shifts, widths, etc.).

The data presents noticeable low-frequency vibrational modes in both the VIS and NIR,

which can be assigned to the excited state of the ASR; their analysis show the difference

between two forms and, moreover, their amplitude- and phase-profiles aid in dissecting the

spectral changes into contributions from ground and excited state bands. In addition,

impulsive vibrational spectroscopy with sub-10fs time resolution has been used to identify the

differences in the ground state Raman active vibrational frequencies of both forms [2].

References: [1] J. C. Venter et al., Science, 304, 66-74 (2004). [2] O. A. Sineshchekov et. al., J. Bio. Chem., 280, 14663-14668 (2006); A. Kawanabe et. al.,

JACS, 129, 8644-8649 (2007); Y. Wada et. al., Chem. Phys. Lett., 453, 105-108 (2008).

Poster 64

Tracking the Ultrafast Wavepacket Motion in Barrierless Cyanine

Photoisomerization by Femtosecond Pump-Dump-Probe Spectroscopy

Zhengrong Wei, Takumi Nakamura, Satoshi Takeuchi, Tahei Tahara

Molecular Spectroscopy Laboratory, Advanced Science Institute (ASI), RIKEN, 2-1

Hirosawa, Wako 351-0198, Japan. Email: zhrwei@riken.jp

Ultrafast reactions often proceed on the potential energy surface (PES) having a very low or

even zero potential barrier. For those reactions, rapid structural change takes place on the

time scale of nuclear motion, and the dynamics can be better described by wavepacket motion

rather than the kinetic population transfer. The wavepacket motion on the excited-state PES

is directly related to the structural evolution in ultrafast reactions. Although this type of

wavepacket motion can provide an intuitive picture of the dynamics of ultrafast reactions, in

reality, we have only very limited knowledge on how the wavepacket evolves on the

barrierless excited state PES.

In this presentation, we report our pump-dump-probe spectroscopic study of the nuclear

wavepacket motion in photoisomerization of a prototype cyanine dye, 1, 1’-diethyl-4, 4’-

cyanine, which is known to have a barrierless PES.1 The wavepacket motion was examined

through the efficiency of the stimulated emission dumping which was evaluated from the

recovery of a ground-state bleaching signal. We found that the dump efficiency exhibited a

finite rise time, and the rise time became longer with decrease of dump photon energy. This

result demonstrates a continuous migration of the leading edge of the wavepacket on the

excited-state PES from the Franck-Condon region toward the sink region. A slowly-decaying

feature of the dump efficiency was also observed. This indicated a considerable broadening of

the wavepacket over a wide range of the potential, which results in a population distribution

spread on the flat S1 PES. The rapid migration as well as broadening of the wavepacket

manifests a continuous nature of the structural dynamics of this ultrafast reaction.2 This work

showed high capability of the pump-dump-probe spectroscopy for quantitative investigation

of the wavepacket motion, and this spectroscopic method enable us to obtain a realistic

picture of the wavepacket motion in ultrafast reactions.

References:

[1] E. Åkesson, H. Bergström, V. Sundström, T. Gillbro, Chem. Phys. Lett. 126 (1986) 385.

[2] Z. R. Wei, T. Nakamura, S. Takeuchi, T. Tahara. (submitted)

Poster 65

Terahertz dynamics and structure of protic ionic liquids

David Turton1, Thomas Sonnleitner2, Glenn Hefter3, Andreas Thoman4, Markus Walther4,

Richard Buchner2, and Klaas Wynne1

1School of Chemistry and WestCHEM, University of Glasgow, G12 8QQ, UK

2Inst. of Physical and Theoretical Chemistry, University of Regensburg, Germany

3Chemistry Department, Murdoch University, Murdoch, W.A. 6150, Australia

4Dept. of Mol. and Opt. Physics, Albert-Ludwigs- Universität. Freiburg, Germany

1david.turton@glasgow.ac.uk, klaas.wynne@glasgow.ac.uk

Protic ionic liquids (PILs) offer great potential as electrolytes for advanced fuel cells. Hence it

is essential to understand how the molecular composition of these liquids determines the

macroscopic properties that are critical to such applications.1

By applying optical-Kerr effect (OKE) and dielectric spectroscopy to imidazolium ILs we

showed2 that we could distinguish the nanoscale heterogeneities, predicted by molecular

dynamics simulations, which are likely to determine the transport properties, conductivities,

thermal conductivities, and heat capacities. Here we study the PILs ethyl-, propyl-, and

butylammonium nitrate over a

range of temperature. The spectra

are remarkably simple and their

interpretation in the context of

simple liquids, mixtures, and

glass-forming liquids should also

give insight into the complex and

poorly understood region of

liquid dynamics where

intramolecular vibrations give

way to diffusional motions.

References: [1] S. Y. Lee, A. Ogawa, M. Kanno, H. Nakamoto, T. Yasuda, and M. Watanabe, Journal of the

American Chemical Society 132 (2010) 9764. [2] D. A. Turton, J. Hunger, A. Stoppa, G. Hefter, A. Thoman, M. Walther, R. Buchner, and K.

Wynne, Journal of the American Chemical Society 131 (2009) 11140.

Poster 66

SO

KE

1 GHz 10 GHz 100 GHz 1 THz 10 THzFrequency

0.01 0.1 1 10 100Wavenumber /cm

-1

libra

tion

relaxation

65 °C 45 °C 25 °C 5 °C -15 °C

ethylammoniumnitrate

Ultrafast Two-Dimensional Infrared Spectroscopy of DNA Oligomers at

Different Hydration Levels

Ming Yang, Łukasz Szyc, and Thomas Elsaesser

Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Strasse 2 A,

D-12489 Berlin, Germany

DNA in an aqueous environment combines quasi-static and fluctuating hydrogen bonded

structures and displays a rich scheme of vibrational couplings. We apply femtosecond two-

dimensional (2D) infrared spectroscopy to discern the different NH stretching excitations of

adenine-thymine base pairs in DNA oligomers, to determine their mutual couplings, and to

study interactions between DNA and the surrounding water shell. The 2D spectra taken for

population times T between 0 and 1.0 ps show NH and NH2 stretching vibration lifetimes of

~0.5 ps, consistent with earlier pump-probe results [1,2]. In the 2D-IR spectra, the

overlapping NH stretching mode of thymine and the symmetric NH2 stretching modes of

adenine are separated via their different line shapes [3]. The slopes of the diagonal peaks

demonstrate an essentially homogeneous broadening of the thymine NH stretching band,

whereas the adenine NH2 stretching modes display a pronounced time-independent

inhomogeneous broadening, pointing to static structural disorder in the DNA structure. We

observe (downhill) vibrational energy transfer from the adenine asymmetric NH2 stretching

vibration at 3350 cm-1 to the thymine NH stretching mode at 3200 cm-1 on a ~0.5 ps time

scale [3]. Upon hydration of the DNA oligomers, the fluctuating water shell induces a limited

spectral diffusion of the different NH stretching excitations. Fluctuations within the water

environment are mapped via 2D spectra of the OH stretching vibration. The behavior of the

water shell is similar to neat water with, however, a slower dynamics of spectral diffusion.

References:

[1] J. R. Dwyer, Ł. Szyc, E. T. J. Nibbering, T. Elsaesser, J. Phys.Chem. B 112 (2008) 11194.

[2] , Ł. Szyc, M. Yang, E. T. J. Nibbering, T. Elsaesser, Angew. Chem. Int Ed. 49 (2010)

3598.

[3] M. Yang, Ł. Szyc, T. Elsaesser, J. Phys. Chem. B 115 (2011) 1262.

Poster 67

Ultrafast Dynamics and Couplings of N-H Stretching Excitations of

Guanosine-Cytidine Base Pairs in Solution

Henk Fidder1, Ming Yang1, Łukasz Szyc1, Katharina Röttger2, Erik T. J. Nibbering1, Thomas

Elsaesser1, Friedrich Temps2

1Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max Born Str. 2A, D-

12489 Berlin, Germany; e-mail: fidder@mbi-berlin.de 2Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel, Olshausenstr. 40,

D-24098 Kiel, Germany

Hydrogen bonded base pairs in solution are important model systems for studying basic

features of nucleobase pairing in DNA. Here, N-H stretching vibrations of guanosine-cytidine

(G•C) base pairs in Watson-Crick geometry are studied in chloroform solution with linear and

ultrafast nonlinear infrared (IR) spectroscopy [1]. The IR-active bands in the linear spectrum

are assigned by combining structural information on the hydrogen bonds in G•C base pairs

with literature results of density functional theory calculations, and empirical relations

connecting frequency shifts and intensity of the IR-active vibrations. A local mode

representation of N-H stretching vibrations is adopted, consisting of νG(NH2)f and νC(NH2)f

modes for free NH groups of G and C, and of νG(NH2)b, νG(NH) and νC(NH2)b modes

associated with N-H stretching motions of hydrogen-bonded NH groups. The couplings and

relaxation dynamics of the N-H stretching excitations are studied with femtosecond mid-

infrared two-dimensional (2D) and pump-probe spectroscopy. The N-H stretching vibrations

of the free NH groups of G and C have an average population lifetime of ~2.4 ps. For the

hydrogen-bonded N-H stretching vibrations a vibrational population lifetime shortening to ≤

0.4 ps is concluded from the pump-probe and 2D-IR experimental results. Analysis of the 2D

spectra indicates ultrafast excitation transfer from the νG(NH2)b mode to the νG(NH) mode.

The temporal evolution of the diagonal spectrum, as well as the ν3-dependence of maxima

along the ν1-axis demonstrate that a predominantly homogeneously broadened band at 3301

cm-1, assigned to νG(NH2)b, overlaps with a significantly broader absorption structure, that is

dominated by inhomogeneous broadening.

References:

[1] M. Yang, Ł. Szyc, K. Röttger, H. Fidder, E. T. J. Nibbering, T. Elsaesser and F. Temps, J. Phys. Chem. B (2011), Article ASAP DOI: 10.1021/jp110561d.

Poster 68

Resonant Stimulated Raman Spectroscopy of the S1 and S* Excited States

of Carotenoids in Light-Harvesting Complex

O. Yoshimatsu1, K. Abe1, R. Nakamura1,2, S. Sakai3, K. Nakagawa2,3, M. Nango2,4,

H. Hashimoto2,4, and M. Yoshizawa1,2,*

1 Department of Physics, Tohoku University, Sendai, Japan, *m-yoshizawa@m.tohoku.ac.jp 2 JST- CREST, Kawaguchi, Saitama, Japan

3 Department of Life and Materials Engineering, Nagoya Institute of Technology, Japan

4 OCARINA, Osaka City University, Osaka, Japan

In photosynthesis, carotenoids play important roles in light harvesting (LH) and

photoprotective functions. The S2 and S1 excited states in carotenoids are important in the LH

function. Recently, another dark state, S*, has been identified in LH complexes [1]. In this

study, vibrational dynamics of the S1 and S* excited states has been investigated by

femtosecond stimulated Raman spectroscopy [2]. Figure 1 shows the Raman signals of the S0

(a), S1 (b), and S* (c) states of spirilloxanthin in LH1 from Rhodospirillum rubrum S1. The

1510 and 1150 cm-1 signals of the S0 state are assigned

to 1 (C=C stretch.) and 2 (C-C stretch.) modes of

spirilloxanthin, respecttively. The S1 and S* signals are

obtained using the resonant Raman pump pulses at 620

nm and 580 nm, respectively, at a delay time of 0.5 ps

after photoexcitation of the S2 state by the 500 nm

pump. The S1 state has the specific 1 mode at 1780 cm-

1 as -carotene in solution [3]. On the other hand, the S*

state shows similar structure with the triplet state [4].

References:

[1] T. Polívka and V. Sundström, Chem. Rev. 104 (2004) 2021.

[2] M. Yoshizawa and M. Kurosawa, Phys. Rev. A61 (1999) 013808.

[3] M. Yoshizawa, H. Aoki, and H. Hashimoto, Phys. Rev. B63 (2001) 180301.

[4] H. Hashimoto and Y. Koyama, Chem. Phys. Lett. 163 (1989) 251.

Poster 69

Fig.1 Stimulated Raman signals

of the S0 (a), S1 (b), and S* (c)

states of spirilloxanthin in LH1.

1200 1400 1600 1800Raman shift (cm-1)

Ram

an S

igna

l

(a)

(c)

(b)

Ultrafast 2-Dimensional Surface Vibrational Spectroscopy of Water at

Lipid Interfaces

Zhen Zhang1, Lukasz Piatkowski1, Huib J. Bakker1, and Mischa Bonn1

1 zhang@amolf.nl, piatkowski@amolf.nl, bakker@amolf.nl, bonn@amolf.nl, FOM Institute

AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands.

A full understanding of the dynamics of water at the interface of lipids is essential for a

molecular-level understanding of biological membranes. Here we present studies of the

structural dynamics of water at the lipid/water interface using ultrafast two-dimensional

surface-specific vibrational spectroscopy.[1] The results reveal that water at lipid interfaces is

structurally heterogeneous. Specifically, at least two sub-ensembles of interfacial water

molecules can be identified: Strongly hydrogen-bonded water molecules that undergo

extremely rapid (<50 fs) vibrational relaxation, and more weakly hydrogen-bonded water

molecules that behave very similar to water at a water-air interface, in terms of energy

relaxation and energy transfer dynamics. We discuss the nature of the strongly hydrogen-

bonded, membrane-bound water molecules, and the implications of the presence of these

water molecules in the lipid membrane bilayers.

Fig. 1 Time-resolved 2D-SFG data for interfacial water at the water-air (left) and water-lipid (right) interfaces at 200 fs delay time between pump and probe pulses. The response of water at the water-lipid interface reflects two types of water: strongly H-bonded water (~2350 cm-1), and water that behaves like water at a water-air interface.

References:

[1] J. Bredenbeck, A. Ghosh, H.K. Nienhuys, and M. Bonn, Acc. Chem. Res. 42 (2009) 1332.

Poster 70

List of Participants

Katrin Adamczyk University of Strathclyde katrin.adamczyk@strath.ac.uk Marco Arrigoni Coherent Marco.Arrigoni@coherent.com John Asbury Penn State University jasbury@psu.edu Satoshi Ashihara Tokyo Univ. of A&T ashihara@cc.tuat.ac.jp Ellen Backus FOM Institute AMOLF backus@amolf.nl Huib Bakker Amsterdam hbakker@amolf.nl Andreas Barth Stockholm University barth@dbb.su.se Mischa Bonn FOM-AMOLF bonn@amolf.nl Eric Borguet Temple eborguet@temple.edu Tiago Buckup Universität Heidelberg tiago.buckup@pci.uni-heidelberg.de Marco Candelaresi Strathclyde marco.candelaresi@strath.ac.uk Christopher Cheatum University of Iowa christopher-cheatum@uiowa.edu Sergey Chekalin Russian Academy of Science chekalin@isan.troitsk.ru Wutharath Chin Université Paris Sud wutharath.chin@u-psud.fr Niklas Christensson University of Vienna niklas.christensson@univie.ac.at Chris Colley Agilent Technologies chris.colley@agilent.com Fleming Crim University of Wisconsin fcrim@chem.wisc.edu Andreas Deeg LMU Munich andreas.deeg@physik.uni-muenchen.de Mariangela Di Donato LENS didonato@lens.unifi.it Arend Dijkstra Kyoto University dijkstra@kuchem.kyoto-u.ac.jp Paul Donaldson University of Zurich p.m.donaldson@pci.uzh.ch Brian Dyer Emory University briandyer@emory.edu Thomas Elsaesser Max-Born-Institut elsasser@mbi-berlin.de Kelly Fransted University of Chicago kafransted@uchicago.edu Kelly Gaffney Stanford University kgaffney@slac.stanford.edu Ziad Ganim TU München ziadga@gmail.com Sean Garrett-Roe University of Zurich s.garrett-roe@pci.uzh.ch Klaus Gerwert Ruhr-Universitaet gerwert@bph.rub.de Eitan Geva University of Michigan eitan@umich.edu Ed Gooding Princeton Instruments egooding@princetoninstruments.com Marloes Groot VU University m.l.groot@vu.nl Alex Gusev Ultrafast Systems alex@ultrafastsystems.com Terry Gustafson Ohio State University gustafson.5@osu.edu Peter Hamm University of Zurich phamm@pci.uzh.ch Juegen Hauer University of Vienna juergen.hauer@univie.ac.at Karin Hauser University of Konstanz Karin.Hauser@uni-konstanz.de Joachim Heberle FU Berlin joachim.heberle@fu-berlin.de Edwin Heilweil NIST edwin.heilweil@nist.gov Jan Helbing University of Zurich j.helbing@pci.uzh.ch Karsten Heyne Free University Berlin karsten.heyne@fu-berlin.de Robin Hochstrasser University of Pennsylvania hochstra@sas.upenn.edu Cho-Shuen Hsieh FOM-AMOLF hsieh@amolf.nl Adriana Huerta Viga University of Amsterdam A.HuertaViga@uva.nl Johannes Hunger FOM Institute AMOLF j.hunger@amolf.nl Neil Hunt University of Strathclyde nhunt@phys.strath.ac.uk James Hynes Ecole Normale Superieure chynes43@gmail.com Janne Ihalainen University of Jyväskylä janne.ihalainen@jyu.fi Kevin Jones MIT kcj@mit.edu Hideki Kandori Nagoya Institute of Technology kandori@nitech.ac.jp Søren Rud Keiding Aarhus University keiding@chem.au.dk John Kennis VU University Amsterdam j.t.m.kennis@vu.nl John King University of Michigan jtking@umich.edu Gregor Knopp Paul Scherrer Institut gregor.knopp@psi.ch Marius Koch University of Geneva marius.koch@unige.ch Jörg Kohl-Landgraf Goethe-Universität Frankfurt landgraf@theochem.uni-frankfurt.de Philip Kraack Universität Heidelberg philip.kraack@pci.uni-heidelberg.de Kevin Kubarych University of Michigan kubarych@umich.edu Hikaru Kuramochi RIKEN h.kuramochi@riken.jp Jennifer Laaser University of Wisconsin jlaaser@chem.wisc.edu

Bernhard Lang University of Geneva bernhard.lang@unige.ch Andrea Lapini University of Florence lapini@lens.unifi.it Joshua Lessing MIT JLessing@mit.edu Tianquan Lian Emory University tlian@emory.edu Chungwen Liang University of Groningen chungwen.Liang@gmail.com Casey Londergan Haverford College clonderg@haverford.edu Tibert van der Loop Universiteit van Amsterdam T.H.vanderloop@uva.nl H Peter Lu Bowling Green State University hplu@bgsu.edu Andras Lukacs University of East Anglia a.lukacs@uea.ac.uk Alexander Malinovsky Institute of Spectroscopy, RAS almalino@isan.troitsk.ru Marie Marek Universität Heidelberg marie.marek@pci.uni-heidelberg.de Domenico Martoccia Bruker Domenico.Martoccia@bruker.ch Aaron Massari University of Minnesota massari@umn.edu Donten Mateusz University of Zurich m.donten@pci.uzh.ch Kamila Mazur Univeristy of East Anglia k.mazur@uea.ac.uk David McCamant University of Rochester mccamant@chem.rochester.edu Steve Meech University of East Anglia s.meech@uea.ac.uk Markus Meuwly University of Basel m.meuwly@unibas.ch Yasuhisa Mizutani Osaka University mztn@chem.sci.osaka-u.ac.jp Shaul Mukamel University of California, Irvine smukamel@uci.edu H. Müller-Werkmeister Uni Frankfurt muellerwerkmeister@biophysik.org Ryosuke Nakamura Osaka University r.nakamura@casi.osaka-u.ac.jp Michel Negrerie Ecole Polytechnique michel.negrerie@polytechnique.fr Keith Nelson MIT kanelson@mit.edu Erik T. J. Nibbering Max Born Institut nibberin@mbi-berlin.de Jennifer Ogilvie University of Michigan jogilvie@umich.edu Masanari Okuno University of Tokyo mokuno@chem.s.u-tokyo.ac.jp Matthijs Panman University of Amsterdam m.r.panman@uva.nl Vlad Pavelyev University of Groningen V.Pavelyev@rug.nl Brandt Pein University of Illinois pein1@uiuc.edu Chunte Peng MIT sampeng@mit.edu Fivos Perakis University of Zurich f.perakis@pci.uzh.ch Lukasz Piatkowski FOM Institute - AMOLF piatkowski@amolf.nl Emanuele Pontecorvo Sapienza Università di Roma emanuele.pontecorvo@roma1.infn.it Ruben Pool FOM Institute AMOLF pool@amolf.nl Sietse van der Post FOM Institute Amolf post@amolf.nl Maxim Pshenichnikov Groningen m.s.pchenitchnikov@rug.nl Markus Raschke University of Colorado markus.raschke@colorado.edu Julien Rehault University of Zurich j.rehault@pci.uzh.ch Roberto Righini University of Florence righini@lens.unifi.it William Rock The University of Iowa william-rock@uiowa.edu Alexander Rodenberg University of Zurich a.rodenberg@pci.uzh.ch Michael Rodgers Ultrafast Systems rodgers@ultrafastsystems.com Matthew Ross University of Michigan mrross@umich.edu Santanu Roy University of Groningen s.roy@rug.nl Almis Serbenta University of Groningen a.serbenta@rug.nl David Skoff University of Wisconsin david.skoff@gmail.com Tahei Tahara RIKEN tahei@riken.jp Jasper van Thor Imperial College London j.vanthor@imperial.ac.uk Keisuke Tominaga Kobe University tominaga@kobe-u.ac.jp Hajime Torii Shizuoka University torii@ed.shizuoka.ac.jp Pascal Tournois FastLite pascal.tournois@fastlite.com Siva Umapathy Indian Institute of Science umapathy_india@yahoo.com Alipasha Vaziri University of Vienna vaziri@imp.ac.at Peter Vöhringer University of Bonn p.voehringer@uni-bonn.de Marten Vos Ecole Polytechnique marten.vos@polytechnique.edu Josef Wachtveitl Goethe University Frankfurt wveitl@theochem.uni-frankfurt.de Amir Wand Hebrew University of Jerusalem amir.wand@mail.huji.ac.il Zhengrong Wei RIKEN zhrwei@riken.jp Daniel Wilcox University of Michigan dewilcox@umich.edu Luuk van Wilderen Goethe University Frankfurt vanwilderen@biophysik.org John Wilson Agilent Technologies john.wilson@agilent.com

Martin Wolf Fritz-Haber-Institut wolf@fhi-berlin.mpg.de Sander Woutersen University of Amsterdam s.woutersen@uva.nl Klaas Wynne University of Glasgow klaas.wynne@glasgow.ac.uk Ming Yang Max Born Institute yang@mbi-berlin.de Masayuki Yoshizawa Tohoku University m-yoshizawa@m.tohoku.ac.jp Martin Zanni University of Wisconsin zanni@chem.wisc.edu Zhen Zhang FOM-Institute AMOLF zhang@amolf.nl Wolfgang Zinth LMU München wolfgang.zinth@physik.uni-muenchen.de