funded by: doe. anh t. le and timothy c. steimle department of chemistry and biochemistry arizona...
TRANSCRIPT
Funded by: DoE.
Anh T. Le and Timothy C. SteimleDepartment of Chemistry and BiochemistryArizona State University, Tempe,AZ 85287 *
Varun Gupta, Corey A. Rice and John P. MaierDept. of Chem. Univ. of Basel, Basel, Switzerland ‡
Sheng H. Lin and Chih-Kai LinDepartment of Applied Chemistry
National Chiao Tung UniversityHsinchu, Taiwan
Visible spectrum of ZrO2
The 66th International Symposium
on Molecular Spectroscopy, June 2011
‡ Swiss National Science Foundation
Motivation• Bonding in transition metal triatomic molecules.
Structure: a) inserted b) T-shape c) superoxide ; M-OO
•Properties of excited states photochemical precesses a) R and b) vibrational frequencies c) electric dipole moments
TiO2 Publications: PCCP 11, 2649 (2009) ; PCCP 12 15018 (2010)
Previous studies (Exp.)
Structure determination of the X1A1 state. = =108.1 R=1.7710 Å
Pure Rot
X1A1 1 = 887 40 cm-1PES anion
Electrostatic deflection Bent
Matrix isolation IR 1 = 884 cm-1 3 = 818 cm-1
Previous studies (Theory)
X1A1 state properties at RCCSD(T)
X1A1 state properties at CASSCF-CCSD(T)
X1A1 & a3B2 state properties at TD-DFT & EOM-CCSD
No predictions for the A1B1 state.
Experimental method-ASU
Well collimatedmolecular beamRot.Temp.<20 K
Pulsed dye laser
PMT
Box-car integrator
Metal target
Pulse valve
•skimmer
Ablation laser
Reagent&
Carrier
•Zr
Optimized for ZrO2
•Long box-car gate width •Low ablation power
Resolution 0.2 cm-1
Monochromator
PMT
Experimental method-Basel
Pulsed OPO laser
Metal target
Pulse valve
•skimmer
Ablation laser
Reagent&
Carrier
•Zr
Resolution 3 cm-1
F2 (157 nm) laser
MCPIon Detector
Mass-Selected REMPI
Observation REMPI spectra a
LIF low resolution
a.Department of Chemistry, University of Basel, Basel, Switzerland
ZrO2 Dispersed Fluorescence
Position of laser
Progression on
Progression on
Progression of
on top of 1Progressi
on on on top
of 3
DLIF
sig
nal
Wavelength (Å)
17041 cm-1
17562 cm-1
17870 cm-1
ZrO2-Dispersed Fluorescence Analysis
• 268 shifts from 13 bands fluorescence down to ground states
))(()(),,( 21
21
31 3121
31321
ki
i kiki
iiE vvvTvvvG
1
2
3
33
22
Experiment Calculation
Here
898(1)
287(2)
808(2)
9.86(52)
3.52(48)a) Zheng & Bowen J.Phys. A (2005) 109, 11521.
Matrixa
884.3
818
B3LYPb
b) Chertihin & Andrews , J. Phys. Chem. (1995) 99, 6356.
CCSD(T)/Lb
887
281
835
906
295
854
RCCSD(T)c
c) Mok, Chau, Dyke & Lee, Chem. Phys. (2008) 458, 11.
909
278
841
TiO2
968(7)
321(4)
frr=Stretch-stretch force constant
Note: 1 3 frr(X1A1)0
X1A1 Parameters:
Excitation Spectra Assignment
(0,0
,0)
Analogy to TiO2 : X1A1(0,0,0) A1B2(v1,v2,v3)
TiO2 A1B2 state: 1= 876(3), 2 = 184(1), 3 = 316(2)
(0,1
,0)
(0,2
,0)
(0,3
,0)
(0,4
,0)
(0,0
,1)
(0,0
,2)
(0,0
,3)
(1,0
,0)
(2,0
,0)
ZrO2-Excited State Analysis • 40 spectral features in excitation spectra were assigned to 45 transitions
))(()(),,( 21
21
31 3121
31321
ki
i kiki
iiE vvvTvvvG
817(4)
149(4)
519(3)
3(2)
4.43(75)
-
8.50(78)
16307(8
)
854.5
181.3
419.7
16753
794.1
181.8
349.6i
13733
867(3)
184(1)
316(2)
17593
Very Poor agreement
1
2
3
12
23
Exp Calculationa TiO2
33
e
LanL2DZ CASSCF
a) Part of the current study S.H Lin & C-K. Lin Nat. Chaio Tung Univ.
Note: 1 >> 3
frr(A1B2) is significant.
ZrO2 A1B2 Parameters:
Spectral Simulation
Exp. iR, (X1A1) and
Exp. i (A1B2) and
Guess R, (A1B2)
GF MatrixMethods
Assume frr(X1A1)=0fr(A1B2)=0
Duschinskytransformation
Transitionwavenumbe
r and FCF calculation
Predicted SpectrumObserved SpectrumVisual comparison
ImprovedR, (A1B2)
Goal: use only experimental info to predict X1A1(0,0,0) A1B2(v1,v2,v3) spectrum
2
3
2
21 00,0 FCF
X1A1(0,0,0)
A1B2(1,2,3)
Two dimensional (2D) overlap integral for the a1 modes.
One dimensional (1D) overlap integral for the b2 mode. Assuming displaced & distorted harmonic
oscillators Analytical expressions: “2D”: Chang. JCP 128, 174111 (2008)
“1D”: Chang. JMolSpec 1232, 1021 (2005)
Normal coordinates of lower state
Normal coordinates of upper state
Coordinate of lower state
Coordinate of upper state
Spectral Simulation (cont.)
DJQQ )~
()~
( 2
1
1
1 BAAX
Need to relate Q(X1A1) to Q(A1B2). Duschinsky transformation:
Essential :
Also, displacement of nuclei:
Wilson’ “B” matrix: “G” “B”“B”T “L” symmetry coor., S Normal coor., Q, transform
Peter Chen’s review article (“Unimol Rxn Dyn” 1994):
Spectral Simulation (cont.)
0.997100
00.93500.3546-
00.35460.9350
J
0
0.5535
0.5185
D
Intensity Transition Moment Squared
Need A1B2/ B1A1vibronic coupling:
Wavefunction:
A1B2 (1, 2 ,odd ) X1A1(0,0,0) =0 (i.e. odd-3 forbidden)
Even-3 transitions
Odd-3 transitions
Adjustable parameter
Vibronic coupling term
Spectral Simulation (cont.)
(cm-1)
PredictedNo vibronic coupling
Predicted with vibronic coupling
Spectral Simulation (cont.)
ObservedGood!
The best structure and coupling for A1B2 state:
•Vibronic coupling term
1.1
•Bond length Re =1.828 Å bond angle =99º
6900 cm-121 10000 cm-1
Too Big !
Spectral Simulation (cont.)
Consistent with TiO2
X1A1
A1B2
B1A1
C1A2
D1B2
E1B1
Summary
•Large reduction in vibrational frequencies upon excitation (like TiO2).
•Odd-3 quanta transition observed (unlike TiO2).
•First recording and analysis of electronic transitions
for ZrO2. •Vibrational parameters benchmarks for future ab initio
•Simulation of excitation spectra in reasonable agreement with observation.