aAP.plied S�r.fc!ce Science D1v1s1on Topical Conference

"!//iiiiiiiiF

Pacific Northwest NATIONAL LABORATORY

SIMS USA

June 19

SURFACE ANALYSI�

• •

39th Symposium on

Applied Surface

Analysis

June 20-22

29th Symposium of the

AVS Pacific

Northwest Chapter

June 20-22

Table of Contents

About AVS 4

EMSL Overview 9

Vendor Exhibit and Sponsors 10

SIMS USA Program 11

Morning Session 13

Afternoon Session 17

Surface Analysis ’18 Wednesday 26

Session I: Functional Thin Films and Heterostructures 28

Session II: In Operando Characterization of Chemical Reactions 32

Surface Analysis ’18 Thursday 38

Session III: Special Session in Honor of Don Baer 40

Session IV: Phenomena on Model Surfaces and 2D Materials 46

Surface Analysis ’18 Friday 51

Session V: Energy Materials 52

Poster Abstracts 60

Welcome to Surface Analysis ‘18 SIMS USA/Applied Surface Analysis/PNWAVS Joint Meeting

On behalf of the organizing committee, we warmly welcome you to the Pacific Northwest National Laboratory campus for the Surface Analysis ’18 Meeting. We hope that colleagues and friends, together with new arrivals in the field, will find the sessions stimulating and that you will create, renew and deepen acquaintance and collaboration throughout the conference.

If there is anything we can do to improve your visit, please visit our reception desk located in the EMSL lobby.

Yingge Du Email: Yingge.Du@pnnl.gov Mark Engelhard Email: Mark.Engelhard@pnnl.gov Conference Co-chairs Pacific Northwest National Laboratory

Program Committee: SIMS USA Christopher Anderton (PNNL) Anna Belu (Medtronic) John Cliff (PNNL) Christopher Szakal (NIST) Nathan Havercroft (ION TOF USA) Greg Fisher (PHI) Amy Walker (University of Texas at Dallas)

AVS ASSD / PNWAVS Líney Árnadóttir (Oregon State Univ.) Kateryna Artyushkova (Univ. of New Mexico) Yingge Du (PNNL) Mark Engelhard (PNNL) David Lee (Washington State Univ.) Vincent S. Smentkowski (GE-GRC) Theva Thevuthasan (PNNL) Xiaodong Xu (Univ. of Washington) Zihua Zhu (PNNL)

Local Arrangements: Connie Grytness: (509) 371-7372 Debbie Krisher: (509) 375-6761 Lisa Havens: (509) 371-6427

EMSL Map

Schedule Overview Tuesday, June 19 – SIMS USA 7:30 a.m. Light continental breakfast, registration, badging 8:00 – 8:15 a.m. Opening Remarks: SIMS USA (Amy Walker)

Welcome from EMSL Director (Harvey Bolton) 8:15 a.m. – 12:00 p.m. Morning Session 9:30 – 10:00 a.m. Break 12:00 – 1:30 p.m. Lunch 1:30 – 5:40 p.m. Afternoon Session 3:30 – 3:50 p.m. Break 6:00 p.m. Welcome Reception and Dinner

Wednesday, June 20 – Surface Analysis ’18 7:30 a.m. Light continental breakfast, registration, badging 8:20 – 8:40 a.m. Opening Remarks: Overview of Sciences at PNNL (Karl Mueller) 8:40 a.m. – 12:00 p.m. Session I: Functional Thin Films and Heterostructures 10:20 – 10:40 a.m. Break (Vendor Exhibit and Refreshments) 12:00 – 1:30 p.m. Lunch 1:30 – 4:20 p.m. Session II: In Operando Characterization of Chemical Reactions 2:50 – 3:20 p.m. Break (Vendor Exhibit and Refreshments) 4:20 – 6:20 p.m. Graduate Student Poster Session and Vendor Exhibit 6:20 p.m. Banquet Dinner

Thursday, June 21 – Surface Analysis ’18 7:30 a.m. Light continental breakfast, registration, badging 8:10 – 10:00 a.m. Session III: Bio- and Nano- Materials in Honor of Don Baer 10:00 – 10:30 a.m. Break (Vendor Exhibit and Refreshments) 12:10 – 1:30 p.m. Lunch 1:30 – 4:20 p.m. Session IV: Phenomena on Model Surfaces and 2D Materials 1:30 – 5:30 p.m. Vendor Exhibit (open to public) 2:50 – 3:20 p.m. Break 4:20 – 5:30 p.m. Undergrad and High School Student Poster Session 5:30 – 7:00 p.m. Buffet Dinner 7:00 – 8:00 p.m. Poster Award and LIGO presentation 8:00 – 9:00 p.m. Career Panel Discussion for Students and Postdocs

Friday, June 22 – Surface Analysis ’18 7:30 a.m. Light continental breakfast 8:20 a.m. – 12:00 p.m. Session V: Energy Materials 10:20 – 10:40 a.m. Break 12:00 – 12:10 p.m. Closing Remarks 12:10 – 1:00 p.m. Lunch 12:20 – 1:00 p.m. PNWAVS Board of Directors Meeting 1:00 – 2:30 p.m. EMSL Tours

Bus Schedule: Pickup location Tuesday Wednesday Thursday Friday Hampton Inn 7:00 am 7:00 am 7:00 am 7:00 am Red Lion Inn 7:15 am 7:15 am 7:15 am 7:15 am EMSL 8:00 pm 8:00 pm 8:00 pm 1:15 pm EMSL 9:00 pm

PNWAVS was founded in 1962. We are one of the local chapters of the AVS, a nonprofit organization which promotes communication, dissemination of knowledge, recommended practices, research, and education in the use of vacuum and other controlled environments to develop new materials, process technology, devices, and related understanding of material properties for the betterment of humanity.

Visit us at: https://www.avs.org/Chapters/Pacific-Northwest

Current Officers and Contacts:

4

PNWAVS Chairs (* denotes AVS Fellow)

AVS ASSD Officers Chair Kateryna Artyushkova Phone: 505-277-2304 Email: kateryna_artyushkova @ avs.org

Chair- Elect Karen Gaskell Phone: 301-405-4999 Email: karen_gaskell @ avs.org

Secretary Richard T. Haasch Phone: 217-244-2974 Email: richard_haasch @ avs.org

Treasurer Peter M. A. Sherwood Phone: 360-306-5649 Email: peter_sherwood @ avs.org

Past Chair Michaeleen Pacholski Phone: 610-244-6302 Email: michaeleen_pacholski @ avs.org

EC Members-at-Large (2018-2020)

Michael T. Brumbach Phone: 505-377-0188 Email: michael_brumbach @ avs.org

Alan M. Spool Phone: 408-717-5700 Email: alan_spool @ avs.org

EC Members-at-Large Early Career (2018-2020)

Jordan Lerach Phone: 814-867-3185 Email: jordan_lerach @ avs.org

EC Members-at-Large (2017-2019)

Mark Engelhard Phone: 509-371-6494 Email: mark_engelhard @ avs.org

Gregory L. Fisher Phone: 952-828-6460 Email: gregory_fisher @ avs.org

EC Members-at-Large Early Career (2017-2019)

Tamlin Matthews Phone: 989-636-6598 Email: tamlin_matthews @ avs.org

EC Members-at-Large (2016-2018)

Jeffry L. Fenton Phone: 763-526-2876 Email: jeff_fenton @ avs.org

Svitlana Pylypenko Phone: 303-384-2140 Email: svitlana_pylypenko @ avs.org

6

KEY BENEFITS u Technical Sessions – delivers practical training in vacuum and equipment technology; materials and interface characterization; and materials processing with:

• 1250+ technical presentations in 15+ parallel oral sessions • 2 poster sessions • 100+ post-meeting online technical Presentations on Demand

u Short Courses, Webinars, and Onsite Training – delivers practical training in vacuum and equipment technology; materials and interface characterization; and materials processing

u Exhibits – showcases 250+ vendors tools, equipment, services, and publications—plus technology spotlight presentations from exhibitors

u Networking – engages professionals from industry, academia, and national labs as well as students at sessions, exhibits, and during social functions like the Welcome Mixer, Awards Ceremony and Reception, and 5k Run

u Professional Development – offers insights on fundraising, professional skills, work/life balance—plus opportunities to attend the business meetings and become involved in leadership of AVS chapters, divisions and groups

u Career Services – connects job seekers and potential employers at the Career Center—benefit from workshops and other activities including Job Information Forum

u Awards – recognizes outstanding scientific research, technological innovation, and leadership at the AVS Awards Ceremony and Reception

See Why AVS is a Must Attend Event!

Have You Considered Attending the AVS International Symposium & Exhibition?Each fall, the weeklong AVS International Symposium and Exhibition brings together more than 2,500 attendees from around the globe to: Engage and Connect - AVS Brings Together a Diverse Community of Scientists and EngineersEmpower Your Career - AVS Provides Professional Growth Activities, Workshops, and TutorialsExpand Your Knowledge - AVS Delivers the Latest Advances in Materials, Processing and Interfaces

WHO ATTENDSAVS is committed to diversity and inclusiveness in our membership, as well as in all activities, events, programs, and services. Scientific and engineering innovation requires bringing together both diverse ideas and people from varied backgrounds who may have different world views and ways of solving problems. AVS works to include and engage members of all groups in our professional Society and seeks to remove obstacles to their professional growth and advancement.

WHAT REGISTRATION PROVIDESu Technical sessions and exhibitsu AVS Events and Activities Mobile Appu Professional development and career services activities, workshops, forums, etc.u Networking activities like the Welcome Mixer, Member Center, Awards Ceremony and Reception,

coffee breaks, lunches, and the Annual 5K RunIn addition, registration fees include annual AVS Membership with the following benefits:u Online access to the AVS Publication Library (JVST A, JVST B, Biointerphases, and Surface Science

Spectra) as well as a subscription to Physics Todayu Online access to the AVS Technical Library (100s of Presentations on Demand, Monographs, Books, etc.)u Monthly AVS member newsletter and announcementsu Online Career Centeru Enrollment in Chapters, Groups, and Divisions and voting privilegesu Discounts on short courses, life insurance, and hotels

UPCOMING SYMPOSIAu October 21-26, 2018, Long Beach, Californiau October 20-25, 2019, Columbus, Ohiou October 25-30, 2020, Denver, Colorado

Make Your Next Critical Professional Connection by Attending AVS - Don’t Miss This Must Attend Event!

www.avs.org8

At EMSL, scientific discovery and technological innovation in environmental molecular sciences are propelled by integrating experimental and computational resources. Researchers are invited to apply for the opportunity to collaborate with nationally recognized experts and use unparalleled state-of-the-art instruments and facilities.

Annual Call for Proposals

• Issued in December/January• Awarded for up to two years• External peer-review process favors research that

integrates experiment and theory, crosses multiplescience themes, and/or is computationally intensive

General Proposals

• Can be submitted any time (no call necessary);however, a proposal may be held until the nextreview cycle for resource availability

• Proposals are peer reviewed against criteria foraward decisions

• Awarded for up to one fiscal year and endsSeptember 30

• Can request access for deadline-driven, rapidturnaround data

• Scope can vary from a single experiment tosubstantial EMSL access

• Awards heavily depend on resource availability

Student Opportunities

• Undergrad, graduate and postdoc opportunitiesposted at http://jobs.pnnl.gov/

• Wiley Distinguished Postdoctoral Fellowship,http://www.emsl.pnnl.gov/emslweb/wiley-distinguished-postdoctoral-fellowship

EMSL Fast Facts

National scientific user facility

More than 150 instruments

High-performance 3.4 teraflop supercomputer

Access available typically at no cost for published research

Sponsored by DOE’s Office of Biological and Environmental Research

Serving nearly 800 ‘users’ a year

Opened in 1997

www.emsl.pnnl.gov

Proudly collaborating, leading and integrating across disciplines and theory and experiment

Vendor Exhibit and Sponsors We would like to thank the following sponsors for their generous contribution toward the success of this conference. Please visit the vendor exhibition in EMSL 1075/1077. We greatly appreciate their support of this symposium.

10

Tuesday, June 19 - SIMS USA Program

7:30 a.m. Light continental breakfast, registration, badging EMSL 1075/1077 8:00 – 8:15 a.m. Introduction and Welcome

Harvey Bolton, EMSL Director EMSL Auditorium

SIMS USA Morning Session Moderator: Amy Walker, University of Texas at Dallas

EMSL Auditorium

8:15 – 9:00 a.m. Tutorial: Formation of atomic, molecular and biomolecular ions in secondary ion mass spectrometry (SIMS): Artifacts and prospects Peter Williams, Arizona State University

9:00 – 9:30 a.m. Invited: Applications of SIMS depth profiling in advanced nano-electronics R&D: Getting to the bottom of materials' problems and challenges Marco Hopstaken, IBM T.J. Watson Research Center

9:30 – 10:00 a.m. Coffee Break EMSL 1075/1077 SIMS USA Morning Session Con’t

Moderator: Lev Gelb, University of Texas at Dallas EMSL Auditorium

10:00 – 10:30 a.m. Invited: The quest for new uranium-based SIMS measurement standards Chris Szakal, NIST

10:30 – 11:00 a.m.

Invited: Relative sensitivity factor and energy filtering effects for mixed actinide sample analysis by SIMS Todd Williamson, Los Alamos National Laboratory

11:00 – 11:30 a.m. Invited: TOF-SIMS investigations into the fundamentals of performance and degradation of solar cell materials and modules Steve Harvey, National Renewable Energy Laboratory

11:30 – 12:00 p.m. Invited: Nanoscale molecular characterization with individual impact secondary ion mass spectrometry Mike Eller, Texas A&M University

12:00 – 1:30 p.m. Lunch EMSL 1075/1077 SIMS USA Afternoon Session

Moderator: Marco Hopstaken, IBM T.J. Watson Research Center EMSL Auditorium

1:30 – 2:00 p.m. Invited: Hybrid SIMS: A new SIMS instrument for high resolution organic imaging with highest mass-resolving power and MS/MS Nathan Havercroft, ION-TOF USA

2:00 – 2:30 p.m.

Invited: Use of MS/MS for molecular surface analysis by TOF-SIMS Scott Bryan, Physical Electronics

2:30 – 2:50 p.m. An accurate depth profiles to support Si-based semiconductor structures manufacturing using low ion impact energy SIMS Olivier Dulac, Cameca SAS

2:50 – 3:10 p.m. High lateral resolution secondary ion mass spectrometry on ZEISS ORION NanoFab Alexander Lombardi, Carl Zeiss Microscopy, LLC

3:10 – 3:30 p.m. Spectral modeling for ToF-SIMS data analysis Wayne D. Jennings, NASA Glenn Research Center

3:30 – 3:50 p.m. Coffee Break EMSL 1075/1077 SIMS USA Afternoon Session Con’t

Moderator: Chris Szakal, NIST EMSL Auditorium

3:50 – 4:10 p.m. Data analysis in thin film characterization: Learning more with physical models Lev Gelb, University of Texas at Dallas

4:10 – 4:40 p.m.

Invited: Molecular imaging of biological and environmental interfaces using liquid SIMS

Xiao-Ying Yu, Pacific Northwest National Laboratory 4:40 – 5:00 p.m. In situ characterization of switchable ionic liquids by liquid ToF-

SIMS and SALVI Juan Yao, Pacific Northwest National Laboratory

5:00 – 5:20 p.m. Insights into the histology of planarian flatworms based on intact lipid information provided by GCIB-ToF-SIMS imaging Tina B. Angerer, University of Washington

5:20 – 5:40 p.m. Chemical imaging of surface modified 3D porous scaffolds Michael. J. Taylor, University of Washington

6:00 p.m. Welcome Reception and Dinner EMSL Bill’s Bistro Bus Schedule:

Pickup location Tuesday Wednesday Thursday Friday Hampton Inn 7:00 am 7:00 am 7:00 am 7:00 am Red Lion Inn 7:15 am 7:15 am 7:15 am 7:15 am

EMSL 8:00 pm 8:00 pm 8:00 pm 1:15 pm EMSL 9:00 pm

12

SIMS USA Abstracts

Tuesday, June 19 Tutorial: Formation of atomic, molecular and biomolecular ions in secondary ion mass spectrometry (SIMS): artifacts and prospects Peter Williams Corresponding Author: pw@asu.edu School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA Secondary ion mass spectrometry is a remarkably diverse analytical field. Primary ion projectiles can range all the way from simple atomic ions such as Ar+, O2

+ and Cs+ to clusters with masses in the millions of daltons; the choice of projectile is dictated by the analytical problem at hand. Similarly, secondary ion species range from simple atomic ions, used in elemental analysis and isotope ratio determination, through cluster species and small molecular fragments, all the way to ions of intact biomolecules such as lipids, peptides and proteins. A common aim in all these areas is to achieve spatially-resolved analyses, in one dimension (depth profiling) or two dimensions (imaging). There is no comprehensive theory that explains ion formation in all (or really in any) of these areas; for atomic ion species what we have instead is a general qualitative understanding of the factors influencing ion formation, sufficient to predict optimized analytical approaches and to rationalize artifacts if they occur. For polyatomic secondary ions and intact biomolecules we have some understanding of the parameters that can optimize molecular survival in the sputtering process but much less understanding of how ions are formed. This talk will review our current understanding of the formation of atomic and molecular sputtered ions. Invited: Applications of SIMS depth profiling in advanced nano-electronics R&D: getting to the bottom of materials' problems and challenges M.J.P. Hopstaken Corresponding Author: marco.hopstaken@us.ibm.com 1.IBM T.J. Watson Research Center, Yorktown Heights (NY), USA Over the last few decades, SIMS depth profiling techniques and instrumentation has tremendously evolved to keep up with developments in advanced CMOS and related nano-electronics technology. I will discuss the main technology drivers, their implications for SIMS characterization, and review some of the analytical challenges and solutions. • Continued dimensional scaling (i.e. lower film thicknesses, ultra-shallow junctions USJ)

demands for progressive improvement of depth resolution. This has been enabled by continuous instrumental developments to provide high-density, stable, and low-impact energy primary ions beams to enable sub-nm depth resolution (i.e. ‘Atomic layer’ SIMS). I will give various applications of high resolution SIMS analysis of thin-film stacks / USJ, routinely employing sub-500 eV ion beams

• Advanced IC development in a manufacturing context demands at-line SIMS metrology with high throughput and reproducibility, often requiring small area analysis on patterned wafers. Key enablers for advances in SIMS metrology are availability of high-density primary ion beams, high level of automation to allow for unattended operation, and instrumental stability / drift correction. I will discuss implications for high-throughput SIMS full wafer mapping and considerations for patterned device wafer

• Paradigm shift towards 3D device architectures (i.e. FinFET) poses one of the greatest challenges, and appears fundamentally incompatible with low-energy (i.e. ‘broad-beam’) SIMS. This can be partially circumvented by averaging over a large regular arrays of FinFET structures, in combination with backfill and planarization to delineate the Fin sidewall (‘SIMS through Fin technique), which we have successfully employed at realistic Fin dimensions and pitch, relevant for 14 nm node and beyond [1]

• Integration of novel and dissimilar material stacks demands novel SIMS calibration methods and/or quantification protocols. Potential solutions to deal with the higher complexity are cross-calibration with absolute external techniques and multi-standard approaches for explicit correction of SIMS yield variations with matrix composition. I will give selected examples for quantification of in-situ doping in SiGex for wide variation in Ge% and different doping species in various III-V compounds

References: [1] M.J.P. Hopstaken et al., Frontiers of Characterization and Metrology (FCMN) 2017 conference proceedings (2017) Invited: The Quest for New Uranium-Based SIMS Measurement Standards

Christopher Szakal, David S. Simons, Jack D. Fassett, Steven Buntin, and Nicholas Ritchie Corresponding Author: cszakal@nist.gov Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, MD U.S.A. Secondary ion mass spectrometry is extensively used within the international nuclear safeguards community for uranium isotopic analysis, owed in large part to its high sensitivity and precision. As such, the corresponding measurement methods are generally well established. However, there are expressed needs in the space, including a lack of particle standards certified for the quantity of uranium to calibrate and test the efficiency of SIMS instrumentation. This presentation will focus on the quest to produce pg-level standards of uranium for these purposes, including the wealth of challenges that need to be overcome to complete such an ambitious endeavor.

14

Invited: Relative Sensitivity Factor and Energy Filtering Effects for Mixed Actinide Sample Analysis by SIMS

Todd L. Williamson1 and Travis J. Tenner2 Corresponding Author: twilliamson@lanl.gov 1.Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM USA 2.Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM USA During nuclear facility inspections, inspectors collect materials intended to show a history of the operations that have taken place within a facility. These materials can be particles obtained using cotton swipes, solid discarded or operationally related nuclear materials, or other items contaminated with nuclear materials. Analysis of these samples is an extremely powerful tool with which to determine facility operations and history. Uranium analysis by SIMS is a mature technique used by the IAEA and its Network of Analytical Laboratories for treaty verification. The analysis of mixed uranium-plutonium particles and solids is not as mature as a capability and has been identified by the IAEA as topic for increased R&D. This presentation will cover two technical topics related to the analysis of mixed uranium-plutonium materials, relative sensitivity factors (RSF) and energy filtering to improve hydride correction. For a material that contains both U and Pu, while both elements will be sputtered and become ionized during SIMS analysis, they will do so with different efficiencies. This ionization difference tends to be sample-type (matrix) dependent. This phenomenon is known as the relative sensitivity factor (RSF). This presentation will discuss our investigations into determining accurate RSF values for U:Pu and U:Np inter-element measurements. With accurate RSF values, which should be universal for a given sample type, the measured inter-isotope ratios can be corrected to their true values. In a mixed actinide sample, there is 239Pu present which will be unresolvable from 238U1H. This will prevent a conventional hydride correction on measurements, and there are not other clean masses in a mixed actinide sample where a hydride signal can be easily measured. Without a hydride correction the measurement of smaller concentration isotopes will have poor accuracy due to interference from large hydride interferences from major isotopes, and 239Pu measurements will be highly inaccurate. The presentation will discuss our use of energy filtering mediated by an intentionally introduced partial pressure of oxygen in the sample analysis chamber, which changes ionization behavior.

(a) (b)

Figure 1 (a) RSF effects due to sample energy offsets for inter-elemental ratios. (b) Oxygen mediated reduction of hydride formation by energy filtering.

Invited: TOF-SIMS investigations into the fundamentals of performance and degradation of solar cell materials and modules Steve Harvey National Renewable Energy Laboratory Corresponding Author: steve.harvey@nrel.gov We have used time-of-flight secondary-ion mass spectrometry (TOF-SIMS) at the National Renewable Energy Laboratory to investigate the performance and reliability of solar cell materials, and we will present some recent work that highlights the versatility of TOF-SIMS. This work includes: 1) Using a combination of 1-D profiling and 3-D tomography to elucidate the fundamentals of incorporating dopants in CdTe solar cells; 2) Multi-scale, multi-technique investigations of photovoltaic module failure including TOF-SIMS to enable insights into the root-cause mechanisms of module degradation at the nanoscale that are observed at the length scale of meters; and 3) Investigations into the performance and stability of hybrid perovskite solar cell devices. Lastly, we will cover some instrumental limitations and known artifacts for hybrid perovskite solar cell devices. Invited: Nanoscale Molecular Characterization with Individual Impact Secondary Ion Mass Spectrometry

Michael J. Eller1, Kavita Chandra2, Emma E. Coughlin3, Teri W. Odom2,3 and Emile A. Schweikert1

Corresponding Author: schweikert@chem.tamu.edu 1. Department of Chemistry, Texas A&M University, College Station Texas 77843, United

States of America 2. Department of Materials Science and Engineering, Northwestern University, Evanston

Illinois 60208, United States of America 3. Department of Chemistry, Northwestern University, Evanston Illinois 60208, United

States of America

SIMS with individual projectiles is a variant of SIMS where instead of a beam of projectiles, projectiles are separated in time and space. This allows for the ejecta from each projectile impact to be collected and mass analyzed. As each projectile emits ions from a nano-volume, this allows for nano-scale mass spectrometry analysis, and allows to test nano-scale molecular homogeneity. For this to be practical multiple ions must be emitted by each impact. Using a nanoparticle (e.g. Au400

4+) as a projectile enhances molecular ion emission by 100 to 1000 times that from atomic bombardment and molecular ion emission is promoted over fragmentation, thus enabling nanoscale molecular characterization. We have previously shown that using individual impacts of 520 keV Au400

4+ (emission area ca. 10 nm in diameter and up to 10 nm in depth) the homogeneity of a mixture of ultra-small nanoparticles differing only by their respective functionalization can be assessed.1 Expanding on this method, here we examine the capability to assess ligand loading on sorted assymetrical nanopartilces. Specifically, gold nanostars functionalized with 15mer poly-thymine DNA. The gold nanostars are up to 100 nm in length and may have 2-10 branches. Dispersing the gold nanostars and impacting them one-by-one, rather than the ensemble, mitigates averaging of differences between particles. Selecting mass spectra from individual impacts based on the number and type of emitted secondaries allows to group impacts occurring on like objects. To determine the relationship

16

between particle geometry and DNA loading, DNA-related ions are quantified in the selected mass spectra. We found that branched particles exhibited increased loading versus spherical particles with similar surface area and determined that positive curvature (convex shape) facilitated additional loading. However, regions of negative curvature (concave shape) where the branch meets the core reduced loading. We hypothesize that the reduced loading is due to steric hinderance between ligand molecules. The methodology described is label free and can universally applied to probe any ligand-nanoparticle interaction. We suggest, improvements to the method can be achieved by using still larger projectiles. We describe here a novel projectile Au2800

+8 for use in SIMS with individual projectiles, which generates more than 30 ions on average per projectile impact, enhancing the capabilities for nano-scale characterization. It was found that with impacts of 1040 keV Au2800

+8 on glycine ~4.4 molecular ions are detected per projectile impact, an increase of >2X compared to 520 keV Au400

+4. For Gramicidin S the yield of the molecular ion increased ~3X. In all cases the emission of molecular species was promoted over fragment ions. These results are promising and suggest that using Au2800

+8 will enhance the sensitivity of SIMS with individual projectiles for nanoscale characterization. This work was supported by the National Science Foundation grant CHE-1308312 (M.J.E., E.A.S.) and award CHE-1507790 (K.C., E.E.C, T.W.O.) [1] Eller, M. J.; Verkhoturov, S. V.; Schweikert, E. A. Anal. Chem. 2016, 88, 7639-7646.

Invited: Hybrid SIMS: A new SIMS instrument for high resolution organic imaging with highest mass-resolving power and MS/MS

Pirkl1, R. Moellers1, H. Arlinghaus1, D. Scurr2, N. Starr2, E. Niehuis1 and N. Havercroft3 Corresponding Author: nathan@iontofusa.com 1. IONTOF GmbH, Muenster, Germany 2. The University of Nottingham, Nottingham, UK 3. IONTOF USA, Chestnut Ridge, NY 10977, USA Secondary ion mass spectrometry (SIMS) offers the possibility to acquire chemical information from submicron regions on inorganic and organic samples. This capability has been especially intriguing for researchers with life science applications. In recent years, the vision to image and unambiguously identify molecules on a sub-cellular level has been driving instrumental and application development. While new ion sources expanded the usability of SIMS instruments for biological applications, SIMS analyzers lacked the required mass resolution, mass accuracy and MS/MS capabilities required for the thorough investigation of these materials. To specifically address the imaging requirements in the life science field a powerful new Hybrid SIMS instrument [1] was developed in a research project by IONTOF and Thermo Fisher ScientificTM , following Prof Ian S Gilmore’s original idea, in close cooperation with the National Centre of Excellence in Mass Spectrometry Imaging (NiCE-MSI), GlaxoSmithKline, and the School of Pharmacy of the University of Nottingham. The instrument combines an OrbitrapTM-based Thermo ScientificTM Q ExactiveTM HF mass analyser with a high-end ToF-SIMS system (IONTOF GmbH). The instrument provides highest mass resolution (> 240,000) and highest mass accuracy (< 1 ppm) with high lateral resolution cluster SIMS imaging.

In this contribution we will illustrate the instrumental design, which is based on a time-of-flight SIMS instrument (TOF-SIMS.5) that is combined with an OrbitrapTM. Secondary ions, generated by primary ion bombardment from liquid metal ion clusters or large gas clusters can be analyzed in either of the mass analyzers. Fast switching between the mass analyzers is achieved by pulsing of a hemispherical electrode. This even allows combined measurement modes using the TOF for very fast imaging and the Orbitrap mass analyzer during intermediate sputtering cycles for generation of spectra with high mass resolution and mass accuracy from the same sample area in a single experiment. First application data including high resolution SIMS spectrometry, MS/MS analyses, high resolution imaging of tissues and depth profiles of biological samples with this new instrument will be presented. From porcine skin samples, for example, single beam depth profiling data were collected, that clearly exhibited different molecular ion signals for different skin layers. This method potentially allows one to measure the permeation of skin for various compounds, e.g. drug molecules. References: [1] The 3D OrbiSIMS – Label-Free Metabolic Imaging with Sub-cellular Lateral Resolution and High Mass Resolving Power’, Passarelli et al., Nature Methods, DOI 10.1038/nmeth.4504 Invited: Use of MS/MS for Molecular Surface Analysis by TOF-SIMS

G.L. Fisher, D. M. Carr, A. A. Ellsworth and S.R. Bryan Corresponding Author: sbryan@phi.com Physical Electronics, 18725 Lake Drive East, Chanhassen, MN 55317 A MS/MS capability was recently integrated into the PHI nanoTOF II instrument to make unknown peak identification easier [1,2]. It allows unambiguous identification of both organic and inorganic peaks above m/z 150, where mass accuracy is not sufficient to identify the composition of a peak by its exact mass [3,4]. A big advantage for TOF-SIMS is that the MS/MS spectrum of a given precursor ion is independent of the primary ion used to generated it. In fact, even MS/MS databases using other sources, such as electrospray, have proven useful for TOF-SIMS MS/MS spectral matching. The effectiveness of using the NIST MS/MS database for TOF-SIMS applications will be discussed. One of the unique aspects of the MS/MS capability described in this presentation is that it uses the same primary ion conditions (pulse width and repetition rate) used for traditional TOF-SIMS. Because of the high transmission of ions into the collision induced dissociation (CID) cell and to the linear TOF detector, MS/MS spectra can be acquired at doses well below the static SIMS limit. This enables molecular identification in the outer monolayer of a solid. Due to the high primary ion beam repetition rate, MS/MS images can be acquired in the same time scale as TOF-SIMS images. Examples will be given where these two unique aspects are important for surface analysis. References: [1] G.L. Fisher, J.S. Hammond, P.E. Larson, S.R. Bryan, R.M.A. Heeren, J. Vac. Sci. Technol. B 34(3) (2016), 03H126-1. [2] G.L. Fisher, A.L. Bruinen, N. Ogrinc Potočnik, J.S. Hammond, S.R. Bryan, P.E. Larson, R.M.A. Heeren, Anal. Chem., 88 (2016), 6433-6440.

18

[3] G.L. Fisher, J.S. Hammond, S.R. Bryan, P.E. Larson, R.M.A. Heeren, Microsc. Microanal., (2017), 1-6. [4] C.E. Chini, G.L. Fisher, B. Johnson, M.M. Tamkun, M.L. Kraft, Biointerphases, 13(3), (2018) 03B409-1. An accurate depth profiles to support Si-based semiconductor structures manufacturing using low ion impact energy SIMS. A. Merkulov 1, O. Dulac1 and D. J. Larson1 1Scientific Marketing / Cameca Sas, 29 Quai Des Gresillons, 92622 Gennevilliers, France Corresponding Author: Alexandre.Merkulov@Ametek.Com

Current semiconductor CMOS technology requires very shallow, high dose dopant profiling with the capability to measure concentration variations from well above the dilute level down to ppm concentration level in the substrate and at a junction depth down to less than ten nanometers. Secondary ion mass spectrometry (SIMS) analysis is challenged by the task of sputtering through shallow multi-component, multi-layered structures at the near surface. Furthermore, the interfaces contained in this region of interest may be modified during the analysis. SIMS analysis accuracy limitations are inherent to the sputtering process itself, or more accurately, due to energetic primary ion – multi-component target interactions. Sputtering yield, as well as the secondary ion yield, may change substantially in thin layer (1-2nm) and at all interfaces (in a planar or vertical structure layout), what makes this region challenging for accurate depth profiling. Accounting of all the effects observed during SIMS depth profiling becomes difficult when technology is moving from planar to 3D pattering procedures. It is well known that lowering the primary ion energy reduces the transient region thickness and number of artefacts associated with sputtering through interfaces. The challenge for SIMS as a metrology for high volume CMOS device manufacturing [1] is to succeed within the constrains ‘as accurate as possible’ and ‘as fast as possible’. Development of SIMS to support device fabrication is based on future development of SIMS protocols for in-line tests of 3D structures. Several protocols are being developed lately, such as 1.5D SIMS [2], and self-focus SIMS [3]. Another interesting approach is to create a SIMS depth profiles library, inherent to the present technology node and compare depth profiles to the library. The application may be limited to one manufacturing site with newly developing processes. However, it provides the information needed to improve the process yield, potentially creating a niche for SIMS analysis for CMOS (and possibly post-CMOS) device production. The paper presents results on accurate determination in depth distribution of ultra-shallow P, Ge and B concentration profiles in planar and 3D structures using low impact energy for O2

+ and Cs+ primary ions. Future development of SIMS instruments for high volume manufacturing, based on SIMS applications above will also be discussed. References: [1] P. van der Heide, J. Vac. Sci Tech B. 36(3) (2018) 03F105-1. [2] W. Vandervorst, C. Fleischmann, J. Bogdanowicz, A. Franquet, U. Celano, K. Paredis,,

A. Budrevich, Mat. Sci. Semicon. Proc. 62, 31–48 (2017). [3] A. Franquet, B. Douhard, D. Melkonyan, P. Favia, T. Conard, W. Vandervorst, Appl.

Surf. Sci. 365, 143–152 (2016).

High Lateral Resolution Secondary Ion Mass Spectrometry on ZEISS ORION NanoFab

Alexander Lombardi1, David Dowsett2, Fouzia Khanom1, Brett Lewis1, Sybren Sijbrandij1 Corresponding Author: alexander.lombardi@zeiss.com 1. Carl Zeiss Microscopy LLC, One Corporation Way, Peabody, MA 01960, USA 2. Luxembourg Ion Optical Nano-Systems Sàrl, Technoport 2, rue du Commerce, L-3895 Foetz, Luxembourg Using a high brightness gas field ion source (GFIS) with helium or neon, the ZEISS ORION NanoFab Helium Ion Microscope (HIM) generates secondary electron (SE) images with high resolution, high contrast, and large depth of field [1]. This is achieved through a small focused probe size of 0.5 and 1.9 nm for helium and neon, respectively. The NanoFab is also capable of fabricating sub-10 nm structures by ion beam sputtering, lithography, and beam-assisted chemical etching or deposition. In collaboration with Luxembourg Institute of Science and Technology and Luxembourg Ion Optical Nano-Systems, we have developed a state-of-the-art Secondary Ion Mass Spectrometer (SIMS) to add surface analysis capabilities to the NanoFab [2-4]. While lateral resolution in SIMS instruments is typically limited by probe size, ZEISS ORION NanoFab SIMS is limited only by beam-sample interactions, allowing for unprecedented lateral resolution [4,5]. Furthermore, the integrated instrument allows for in-situ correlative imaging by layering elemental maps over ultra-high resolution SE images. Here, we will describe the technology of the spectrometer and review instrument performance, presenting several application examples in materials science. We will also demonstrate better than 20 nm lateral resolution of the NanoFab SIMS using the nanoscale stripe pattern from the well-established BAM-L200 standard [6]. References: [1] G. Hlawacek, A. Gölzhäuser, Helium Ion Microscopy, Springer, 2017 [2] T. Wirtz, N. Vanhove, L. Pillatsch, D. Dowsett, S. Sijbrandij, J. Notte, Appl. Phys. Lett. 101 (4) (2012) 041601-1-041601-5 [3] D. Dowsett, T. Wirtz, Anal. Chem. 89 (2017) 8957-8965 [4] T. Wirtz, D. Dowsett, P. Philipp, Helium Ion Microscopy, edited by G. Hlawacek, A. Gölzhäuser, Springer, 2017 [5] T. Wirtz, P. Philipp, J.-N. Audinot, D. Dowsett, S. Eswara, Nanotechnology 26 (2015) 434001 [6] Bundesanstalt für Materialforschung und -prüfung (BAM). https://rrr.bam.de/RRR/Content /EN/Downloads/RM-certificates/RM-cert-layer-and-surface/bam_l200.html

20

Spectral Modeling for ToF-SIMS Data Analysis

Wayne D. Jennings Corresponding Author: wayne.d.jennings@nasa.gov NASA Glenn Research Center, Cleveland, OH, USA. The analysis and interpretation of data from Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) is often complicated and difficult. Even with modern high resolution instruments, peak overlap issues persist. Compounding the problem is the occurrence of “adduct” species which may be formed during the sputtering process, especially with inorganic samples. In particular H and C adducts may make straightforward interpretation of the data difficult. A method of spectral modeling has been developed to aid in the interpretation of ToF-SIMS data. The procedure uses a table of natural isotopes to build up a model spectrum to be compared with the actual data. Weights for the isotopes and adducts are optimized through the Excel “Solver” program in a spreadsheet format. The “Solver” attempts to minimize a goodness of fit parameter which is a simple variance term. Results are presented for ToF-SIMS data of Mo-Ti wire samples with suspected hydride species present. Results in the Mo isotope region of the spectrum confirm the normal distribution of Mo and Ti2, with contributions to the spectrum from several hydride forms. Additional spectral analyses are presented showing the treatment of isotopic enrichment and detector saturation of large peaks. Data Analysis in Thin Film Characterization: Learning More With Physical Models

Lev D. Gelb and Amy V. Walker Corresponding Author: lev.gelb@utdallas.edu Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX USA Chemical imaging methods, including imaging mass spectrometry (MS), are increasingly used for the analysis of samples ranging from biological tissues to electronic devices. Most chemical analyses for advanced materials, nanosystems, and thin films involve energetic beams of primary ions or electrons. These unavoidably cause chemical damage, including surface roughening, which confuses data interpretation. In secondary ion mass spectrometry (SIMS) matrix effects can be significant, in which the signal obtained from a given species may change depending on its surroundings. All these phenomena lead to the same issue: the data measured are not necessarily representative of the elements or species originally present, or their original locations. These effects can sometimes be exploited to provide new information or increased sensitivity, as in matrix-enhanced SIMS and the determination of overlayer thicknesses from attenuation of XPS substrate intensity. We discuss analysis of such data using maximum a posteriori (MAP) reconstruction based on physically motivated models, and contrast this approach with statistical dimensionality-reduction techniques such as Principal Components Analysis. We demonstrate the MAP approach using several “real world” examples including the analysis of aniline dyes used in paper production. We present progress towards the quantitative extraction of chemical concentration profiles, component spectra, sample topography and other information from imaging mass spectrometry data in the presence of matrix effects. These include systems that demonstrate "weak" matrix effects, such as mixed self-assembled monolayers, and “strong” matrix effects such as those observed in ionic

liquid matrix enhanced secondary ion mass spectrometry. Finally we discuss the extension of this approach to other analytical methods, such as X-ray photoelectron spectroscopy (XPS). Invited: Molecular imaging of biological and environmental interfaces using liquid SIMS

Xiao-Ying Yu1 Corresponding Author: xiaoying.yu@pnnl.gov 1. Pacific Northwest National Laboratory, Earth and Biological Sciences Directorate, Richland,

WA 99354, USA.

We invented a vacuum compatible microfluidic interface, System for Analysis at the Liquid Vacuum Interface (SALVI), to enable direct observations of liquid surfaces and liquid-solid interactions using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and a variety of spectroscopy and microscopy characterization techniques [1, 2]. SALVI was recently applied to investigate biological interfaces in living biofilms and co-cultured microbial communities. In this talk, three recent studies will be presented using in situ liquid ToF-SIMS, light microscopy, and fluorescence microscopy. First, Shewanella wild type and mutant were exposed to environmental stressors such as toxic heavy metal ions (i.e., Cr (VI)) and silver nanoparticles. The response of biofilm and its extracellular polymeric substance (EPS) to the environmental perturbation was investigated using in situ liquid SIMS coupled with structured illumination microscopy (SIM) [3]. Second, a complex microbial community consisting of syntrophic Geobacter metallireducens and Geobacter sulfurreducens was investigated. Electron donor and electron acceptor in this co-cultured system were characterized initially using the traditional SIMS dry biological sample preparation approach [4] followed by in situ liquid SIMS and confocal laser scanning microscopy (CLSM). Lastly, we demonstrate the observation of proton coupled electron transfer in riboflavin reduction using our unique electrochemical cell and dynamic in situ liquid SIMS. Correlative imaging is employed to achieve a more holistic view of complexed microbial systems across different space scales. Our results demonstrate that interfacial chemistry involving living microbial systems can be studied from the bottom up based on microfluidics, potentially providing more important understanding in system biology and environmental microbiology [5]. References: [1] L. Yang, et al.. Probing liquid surfaces under vacuum using SEM and ToF-SIMS, Lab Chip 11(15) (2011), 2481-4. [2] X.-Y. Yu, et al., Imaging liquids using microfluidic cells, Micro. & Nano. 15(6) (2013), 725-44. [3] Y. Ding, et al., In situ molecular imaging of the biofilm and its matrix, Anal. Chem. 88(22) (2016), 11244-52. [4] W. Wei, et al., Characterization of syntrophic Geobacter communities using ToF-SIMS, Biointerfaces. 12(5) (2017), 05G601. [5] We acknowledge support from the PNNL Laboratory Directed Research and Development fund and the EMSL Strategic Science Area (SSA). Instrument access to the DOE BER EMSL user facility was under the general user proposal 50093.

22

In situ Characterization of Switchable Ionic Liquids by Liquid ToF-SIMS and SALVI Juan Yao1, David Lao2, Yufan Zhou3, Satish Nune2, David Heldebrant2; Zihua Zhu3, Xiao-Ying Yu1 Corresponding Author: xiaoying.yu@pnnl.gov 1. Pacific Northwest National Laboratory, Earth and Biological Sciences Directorate, Richland, WA 99354, USA. 2. Pacific Northwest National Laboratory, Energy and Environment Directorate, Richland, WA, 99354, USA. 3. Pacific Northwest National Laboratory, W. R. Wiley Environmental Molecular Science Laboratory, Richland, WA. 99354, USA

Switchable ionic liquids (SWILs) derived from organic bases and alcohols are attractive due to their applications in gas capture, separations, and nanomaterial synthesis. However, their exact solvent structure still remains a mystery. We present the first chemical mapping results of the solvent structure of two SWILs using in situ liquid time-of-flight secondary ion mass spectrometry (ToF-SIMS), enabled by a vacuum compatible microfluidic interface, System for Analysis at the Liquid Vacuum Interface (SALVI) [1, 2]. The first system consists of two components including 1,8-diazabicyclod [5.4.0] undec-7-ene (DBU) and 1-hexanol [3] and the second system has a single component of 1-((1,3-dimethylimidazolidin-2-ylidene)amin)propan-2-ol (koechanol) as both the acid and base. SWIL chemical speciation is found to be more complex than the known stoichiometry. Dimers and ionic clusters have been identified in SIMS spectra; and confirmed to be the chemical species differentiating from non-ionic liquids via spectral principal component analysis. In situ chemical mapping discovers two coexisting liquid phases and a molecular structure vastly different from conventional ionic liquids when the SWIL is loaded with an acidic gas like carbon dioxide (CO2). Our unique in situ molecular imaging has advanced the understanding of SWIL chemistry and how this “heterogeneous” liquid structure may impact its physical and thermodynamic properties and associated applications in carbon capture and green solvent. References: [1] L. Yang, et al., Probing liquid surfaces under vacuum using SEM and ToF-SIMS, Lab Chip 11(15) (2011), 2481-4. [2] L. Yang, et al., Making a Hybrid Microfluidic Platform Compatible for In Situ Imaging by Vacuum-Based Techniques, J VAC SCI TECHNOL A, 29(6) (2011), 061101 [3] J. Yao, et al., Two coexisting liquid phases in switchable ionic liquids, Phys. Chem. Chem. Phys. 19(34) (2017), 22627-22623

Insights into the histology of Planarian flatworms based on intact lipid information provided by GCIB-ToF-SIMS imaging

Tina B. Angerer1, Neil Chakravarty1, Michael J. Taylor1, Daniel J. Graham1, Eric H. Chudler1, Lara J. Gamble1

Corresponding Author: angerer@uw.edu 1. Department of Bioengineering, University of Washington, Seattle WA, USA. Planarian flatworms are known as the masters of regeneration, “immortal under the edge of the knife,” re-growing an entire organism from as little as 1/279th part of their body and seemingly unable to die of old-age.[1] The proteomic basis of the regeneration process has been studied extensively but there is next to no knowledge about the planarian lipodome. In an ongoing research project we elucidate some of these knowledge gaps using ToF-SIMS imaging mass spectrometry in combination with microscopy and imaging PCA. ToF-SIMS is capable of gathering intact lipid information from small biological structures such as a single cell layers, and studying the location and identity of lipid and fatty acid species in planarian tissue sections.[2] Our data shows that different organs and structures within those organs in planarians can be distinguished based on their unique lipid profiles (Figure 1). Planarians contain unusual fatty acid species (ether containing and odd carbon chain numbered fatty acids) and an abundance of poorly understood

lipid species such as phosphatidylserine plasmalogen (Figure 1_D, PS(P-16:0/16:0) in pharynx epithelial cells) synthesized from fatty alcohols instead of fatty acids. There is also evidence that planarian intestines contain a new, yet unidentified class of lipids (Figure 1_C), which will require additional experimentation to be verified. Figure 1 Localization of different lipid species

in planarian organs. A) Light microscope image of longitudinal planarian tissue section on ITO-glass, B-F) false color lipid distribution images of the mass stated in the image, generated using ToF-SIMS of this tissue section. B) PI(18:0/20:4) highlighting brain and reproductive organs, C) m/z 879.60 uniquely present in the intestines, D) PS(P-16:0/16:0), ectodermal epithelial cells in skin and pharynx, E) PI(18:0/22:5), testes, F) PE-Cer(d34:1) and m/z 947.69, male reproductive organs. Acknowledgements: Work done at NESACBIO with funding provided by NIH P41 EB002027. References: [1] T. Morgan, Development Genes and Evolution 1898, 7, 364-397. [2] T. B. Angerer, M. D. Pour, P. Malmberg, J. S. Fletcher, Anal Chem 2015, 87, 4305-4313.

24

Chemical Imaging of surface modified 3D porous scaffolds

Michael. J. Taylor1, Daniel. J. Graham1 and Lara. J. Gamble1 Corresponding Author: lgamble@uw.edu 1.NESAC/BIO, Department of Bioengineering, University of Washington, Seattle, WA 98105 Three-dimensional (3D) porous materials are applied in a variety of areas within materials science1. Pores in catalysts provide a high surface reaction area, pores in biofilters facilitate fluid movement for ligand capture, and pores in tissue engineering constructs allow for cellular ingress and vascularization. These materials often rely on surface modifications to add specific functionality to the scaffolds for the intended application. The reliability of these materials can be greatly improved by the ability to verify the presence and distribution of surface modifications. This is particularly important since often the successful functionality of these materials is related to the ability of these modifications to reach all surfaces of the pores. Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is a label-free powerful surface analysis tool that can be used to image the molecular composition2 of cells, tissues and polymers. Porous 3D materials however, are non-ideal for ToF-SIMS analysis as the technique is highly surface-sensitive. Topography on the order of microns can inhibit the ability to determine the distribution of secondary ions related to surface modifications. To solve this problem we have developed a methodology for filling voids based on embedding porous materials with poly(vinyl alcohol) (PVA), followed by freezing and cryo-sectioning (Figure 1). Here, we demonstrate the versatility of this method by characterizing fluorocarbon (FC) films deposited throughout poly(caprolactone) (PCL) scaffolds using octofluoropropane (C3F8) plasma enhanced chemical vapor deposition (PECVD). We use ToF-SIMS imaging to map the distribution of FC plasma treatment though PCL scaffolds demonstrating that longer treatment times deposits more uniform coatings whilst shorter treatment times results in a gradient distribution of FC. This methodology increases our ability to characterise surface modifications in materials with complex geometries and will aid in the design and modification of porous materials. References: Acknowledgements: Work performed at NESACBIO with funding provided by NIH P41 EB002027. Thanks of also given to E. R. Fisher and her group for providing samples.

[1] X. Yang, L. Chen, Y. Li, J. Rooke, Hierarchically Porous Materials: Synthesis Strategies and Structure Design. Chem. Soc. Rev. 2017, 46 (2), 481–5 [2] J. Fletcher. Latest Applications of 3D ToF-SIMS Bio-Imaging. Biointerphases 2015, 10 (1), 18902

Wednesday, June 20 - Surface Analysis ’18 Program

7:30 a.m. Light continental breakfast, registration, badging EMSL 1075/1077 8:20 – 8:40 a.m. Opening Remarks and Overview of Sciences at PNNL

Karl Mueller, Pacific Northwest National Laboratory EMSL Auditorium

Session I Functional Thin Films and Heterostructures Moderator: Tiffany Kaspar, Pacific Northwest National Laboratory

EMSL Auditorium

8:40 – 9:20 a.m. Invited: Growth, disorder and carrier localization in hybrid MBE-grown stannate films and heterostructures Bharat Jalan, University of Minnesota

9:20 – 9:40 a.m. Epitaxial growth and characterization of CrFe2O4 on MgAl2O4 Mark Scafetta, Pacific Northwest National Laboratory

9:40 – 10:20 a.m. Invited: Probing electronic structure and reaction intermediates in situ Kelsey A. Stoerzinger, Pacific Northwest National Laboratory

10:20 – 10:40 a.m. Coffee Break: Vendor Exhibit and Refreshments EMSL 1075/1077

Functional Thin Films and Heterostructures Moderator: Kelsey Stoerzinger, Pacific Northwest National Laboratory

EMSL Auditorium

10:40 – 11:20 a.m. Invited: Electric field control of ionic evolution: A novel strategy to re-design materials Pu Yu, Tsinghua University

11:20 – 11:40 a.m. Brownmillerite phase formation and evolution: Bottom up and top down Le Wang, Pacific Northwest National Laboratory

11:40 – 12:00 p.m. High throughput sputtering for ternary transition metal nitride alloys Bethany Matthews, Oregon State University

12:00 – 1:30 p.m. Lunch EMSL 1075/1077 Session II In Operando Characterization of Chemical Reactions

Moderator: Xin Zhang, Pacific Northwest National Laboratory EMSL Auditorium

1:30 – 2:10 p.m. Invited: Investigation of alloy surface oxidation using ambient pressure x-ray photoelectron spectroscopy Gregory S. Herman, Oregon State University

2:10 – 2:30 p.m. Hydrogen activation and spillover on single palladium atoms supported on Fe3O4(001) surface Nassar Doudin, Pacific Northwest National Laboratory

2:30 – 2:50 p.m. Phase imaging AFM to observe liquid phase heterogeneous hydrogenation in operando Peter H. Pfromm, Washington State University

2:50 – 3:20 p.m. Coffee Break: Vendor Exhibit and Refreshments EMSL 1075/1077

In Operando Characterization of Chemical Reactions Moderator: David Lee, Washington State University

EMSL Auditorium

3:20 – 4:00 p.m. Invited: Imaging and chemical probing of catalytic surface reactions with sub-nanoscale lateral resolution Norbert Kruse, Washington State University

4:00 – 4:20 p.m. Understanding solid transformation of akaganéite to maghemite and hematite by in situ transmission electron microscopy Xin Zhang, Pacific Northwest National Laboratory

4:20 – 6:20 p.m. Poster Session: Graduate Poster Competition Shuttha Shutthanandan, Pacific Northwest National Laboratory

EMSL Lobby

6:20 p.m. BBQ Banquet EMSL Bill’s Bistro

26

Bus Schedule: Pickup location Tuesday Wednesday Thursday Friday Hampton Inn 7:00 am 7:00 am 7:00 am 7:00 am Red Lion Inn 7:15 am 7:15 am 7:15 am 7:15 am

EMSL 8:00 pm 8:00 pm 8:00 pm 1:15 pm EMSL 9:00 pm

Surface Analysis ‘18 Abstracts

Wednesday, June 20 Invited: Growth, Disorder and Carrier Localization in Hybrid MBE-grown Stannate Films and Heterostructures Bharat Jalan Corresponding Author: bjalan@umn.edu Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, U.S.A. In this talk, I will review the grand challenges of the synthesis of metal oxides thin films containing elements of low oxidation potential. I will present our group’s effort to address these challenges using a new radical-based hybrid MBE approach. Using Stannate (BaSnO3 and SrSnO3) as a model material system, I will present a detailed growth study of epitaxial, phase-pure, stoichiometric (Ba,Sr)SnO3 films using hexamethylditin, (CH3)6Sn2 (HMDT) as a tin precursor, elemental solid source for Sr and Ba, and a rf plasma source for oxygen. Combined with a battery of structural characterization techniques, we will present a comprehensive electronic transport study of La-doped BaSnO3 and SrSnO3 and will discuss the important role of structural defects such as dislocations, and non-stoichiometry, and dopant concentration on electronic properties. We will also discuss different scattering mechanisms in La-doped BaSnO3, which limits the room temperature electron mobility. Finally, we will present pathways to enhance electron mobilities towards high room temperature mobility oxide heterostructures using defect-managed thin films and interfaces. Work supported by the NSF, and AFOSR YIP Program. Epitaxial Growth and Characterization of CrFe2O4 on MgAl2O4

Mark D Scafetta, Tiffany C Kaspar, Timothy C Droubay, Scott A Chambers Corresponding Author: mark.scafetta@pnnl.gov Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, United States CrFe2O4 is a spinel structured crystal with interesting magnetic, electronic and photophysical properties. However, CrFe2O4 is among the least studied of the transition metal spinels. Part of this gap in research lies in the lack of availability of high quality single crystals. On the thin-film side, this can be related to the scarcity of suitable single crystal substrates for epitaxial growth. Magnesia or MgO has a very favorable lattice mismatch (~0.344%) but Mg diffusion from the substrate into the epitaxial CrFe2O4 film becomes significant at deposition temperatures as low as 250°C. The spinel MgAl2O4 is isostructural with CrFe2O4, and contains less Mg, but it also has a much smaller lattice constant and, thus, much higher lattice mismatch (>5% compressive). Here we report on the synthesis and challenges associated with molecular beam epitaxial growth of magnetite and CrFe2O4 on spinel compared with magnesia. A novel method for cation concentration determination is presented and scrutinized. Surface chemistry and structure, optical absorption, out-of-plane lattice constants, and other material properties are examined as a function of growth conditions, reversible oxidation, strain, and Cr substitution.

28

Invited: Probing electronic structure and reaction intermediates in situ

Kelsey A. Stoerzinger1 Corresponding Author: kelsey.stoerzinger@pnnl.gov 1. Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA USA Electrocatalysts are important constituents in numerous energy conversion and storage processes. Reactants adsorb onto the electrocatalyst surface, where the interplay of electronic states results in a lower activation barrier for the transfer of electronic and ionic species in the reaction pathway to product formation. Rational design of electrocatalysts with greater activity for higher efficiency devices requires an understanding of the material’s electronic structure in situ, as well as the reaction intermediates involved. Many surface science techniques, such as X-ray photoelectron spectroscopy (XPS), collect information from inherently surface-sensitive low-energy processes, requiring operation in ultrahigh vacuum. This constraint is lifted for ambient pressure XPS,1 which can probe the surface in equilibrium with the gas phase at pressures up to ~a few Torr, or with thin liquid layers using a higher incident photon energy. We will discuss the insights obtained with this technique regarding the electronic structure of perovskite oxide electrocatalysts in an oxidizing or humid environment,2 as well as the reaction intermediates of relevance to oxygen electrocatalysis.3 We will then extend the technique to probe electrocatalysts in operando,4 driving current through a thin layer of liquid electrolyte and employing a tender X-ray source. References: [1] K.A. Stoerzinger, W.T. Hong, E.J. Crumlin, H. Bluhm, and Y. Shao-Horn, Insights into Electrochemical Reactions from Ambient Pressure Photoelectron Spectroscopy, Accounts of Chemical Research (2015) 2976-2983. [2] K.A. Stoerzinger, Y. Du, K. Ihm, K.H.L. Zhang, J. Cai, J.T. Diulus, R.T. Frederick, G.S. Herman, E.J. Crumlin, S.A. Chambers, Impact of Sr-Incorporation on Cr Oxidation and Water Dissociation in La(1-x)SrxCrO3, Advanced Materials Interfaces (2018) 1701363. [3] K.A. Stoerzinger, W.T. Hong, X. Wang, R.R. Rao, S.P.B. Subramanyam, C. Li, Ariando, T. Venkatesan, Q. Liu, E.J. Crumlin, K.K. Varanasi, Y. Shao-Horn, Decreasing the Hydroxylation Affinity of La(1-x)SrxMnO3 Perovskites To Promote Oxygen Reduction Electrocatalysis, Chemistry of Materials (2017) 9990–9997. [4] K.A. Stoerzinger, M. Favaro, P.N. Ross, J. Yang, Z. Liu, Z. Hussain, E.J. Crumlin, Probing the Surface of Platinum during the Hydrogen Evolution Reaction in Alkaline Electrolyte, Journal of Physical Chemistry B (2018) 864–870.

Invited: Electric Field Control of Ionic Evolution: A Novel Strategy to Re-design Materials

Pu Yu Corresponding Author: yupu@tsinghua.edu.cn 1. State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China

2. RIKEN Center for Emergent Matter Science (CEMS), Wako 351-198, Japan. Electric-field control of phase transformation with ion transfer is of great interests in materials science with enormous practical applications. Due to the strong electron-ion interaction, the ionic evolution would naturally have dramatic influence on material functionalities. In this talk, I will first present a reversible and nonvolatile electric-field control of oxygen and hydrogen ion evolutions within the model system of brownmillerite SrCoO2.5 by ionic liquid gating [1]. Due to the selectively controllable ionic evolutions, we achieved a tri-state phase transformations among SrCoO2.5 and its counterpart of perovskite SrCoO3-δ and a hitherto-unexplored HSrCoO2.5 phase. Because of the extremely distinct magnetic, electrical and optical properties among these three phases, this result forms solid foundation for conceptually new tri-state magnetoelectric and electrochromic effects. Along this vein, we further demonstrate the manipulation of metal-insulator transition and enhanced superconductivity through electric-field induced protonation in WO3 [2] and iron-based superconductors [3], respectively. Finally, using Co/SrCoO2.5 as model system, I will introduce a new strategy to achieve the room temperature electric-field control of magnetic state in the Co layer accompanied by the bipolar resistance switch [4]. In this case, the electric field-controlled oxygen evolution leads to oxygen ion accumulation (gating) at the interface, in the same manner as the conventional charge-gating device. As the consequence, the interfacial oxygen contents modulate the magnetic interaction within the Co surface layer and eventually results in the intriguing magnetoelectric coupling. We envision that the ionic evolution brings in a new tuning knob to manipulate the coupling and correlation between charge, spin, orbital and lattice degrees of freedom and paves a new playground for the discovery of novel materials and rich functionalities. References: [1] N. P. Lu, P. Zhang, Q. Zhang, R. Qiao, Q. He, H. –B. Li, Y. J. Wang, J. W. Guo, D. Zhang, Z. Duan, Z. L. Li, M. Wang, S. Z. Yang, M. Z. Yan, E. Arenholz, S. Y. Zhou, W. L. Yang, L. Gu, C. W. Nan, J. Wu*, Y. Tokura, P. Yu*, Electric-field control of tri-state phase transformation with a selective dual-ion switch, Nature 546 (2017), 124 [2] M. Wang, S. Shen, J. Y. Ni, N. P. Lu, Z. L. Li, H. B. Li, S. Z. Yang, T. Z. Chen, J. W. Guo, Y. J. Wang, H. J. Xiang and P. Yu*, Electric-Field Controlled Phase Transformation in WO3 Thin Films through Hydrogen Evolution, Adv. Mater. 29 (2017) 1703628. [3] Y. Cui, G. Zhang, H. -B. Li, H. Lin, X. Zhu, H. -H. Wen, G. Q. Wang, J. Z. Sun, M. W. Ma, Y. Li, D. L. Gong, T. Xie, Y. H. Gu, S. L. Li, H. Q. Luo, P. Yu*, W. Q. Yu*, Protonation induced high-Tc phases in iron-based superconductors evidenced by NMR and magnetization measurements, Science Bulletin 63 (2018), 11 [4] H. B. Li, N. P. Lu, Q. Zhang, Y. J. Wang, D. Q. Feng, T. Z. Chen, S. Z. Yang, Z. Duan, Z. L. Li, Y. J. Shi, W. C. Wang, W. H. Wang, K. Jin, H. Liu, J. Ma, L. Gu, C. W. Nan and P. Yu*, Electric-field control of ferromagnetism through oxygen ion gating, Nature Communications 8 (2017), 2156

30

Brownmillerite Phase Formation and Evolution −Bottom Up and Top Down Le Wang1, Zhenzhong Yang1, Mark E. Bowden2, Mark D. Scafetta1, Yingge Du1 Corresponding Author: yingge.du@pnnl.gov 1Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States 2 Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, USA Recently, brownmillerite (BM) phase oxides are of particular interest as they accommodate a large number of ordered oxygen vacancies on regular perovskite lattice sites. Such vacancies produce both oxygen-ion conduction and electronic conduction, and the former could be exploited in electrolytes in solid-oxide fuel cells and in oxygen-separation membranes. So a bettering understanding the BM phase formation and evolution process will give us further insight into the oxygen-diffusion paths of solid oxygen-ion conductors. Here, we report on the epitaxial growth of high quality SrFeO3-δ (SFO) single crystalline films on LaAlO3 (001) substrates by pulsed laser deposition. By tuning the deposition oxygen pressure and post-annealing, the orientation of the oxygen vacancy channels (OVCs) in the BM-SFO structure can be converted from a horizontal to a perpendicular direction related to substrate surface direction via the XRD and TEM measurements. For the BM-SFO films deposited under 0.01 mTorr, all the OVCs are along the horizontal direction while a certain portion of the perovskite phase SFO (P-SFO) still exists near the SFO/LAO interface, which contributes some electrical conductivity and optical non-transparent characteristic. The proportion of this P-SFO portion increases and some perpendicular direction OVCs appear when increasing the deposition oxygen pressure. However, for the BM-SFO film deposited under 300 mTorr and postannealed under 0.01 mTorr, most of the OVCs are along the perpendicular direction. In-plane transport and ellipsometry measurements confirm that the BM-SFO with perpendicular OVCs shows the higher resistivity and larger optical transition energy. Further measurements and theoretical calculation results are ongoing. High Throughput Sputtering for Ternary Transition Metal Nitride Alloys

Bethany Matthews1, Elisabetta Arca2, Stephan Lany2, John Perkins2, Andriy Zakutayev2, and Janet Tate1 Corresponding Author: matthewb@oregonstate.edu 1. Oregon State University Physics Department, Corvallis, Oregon, USA. 2. National Renewable Energy Laboratory, Golden, Colorado, USA. Advances and break throughs in material research frequently require thorough and often slow exploration of many different material compounds, particularly with the study of thin films. Sputtering is a high energy deposition technique that has many uses in research and development of thin films, which recently has been used in high-throughput investigations of compositional variations in many material systems due to its ability to configure multiple material targets for co-sputtering. Additionally, new technologies in characterization tools allow for quick spatial mapping of these material libraries, significantly accelerating the discovery and characterization process. One example of this high-throughput process are new ternary transition metal nitride structures predicted by theorists at the National Renewable Energy Laboratory and Lawrence

Berkeley National Laboratory. Here we explore the system ZnxW1-xN, which is predicted to have a metastable wurtzite phase stable at the composition Zn0.75W0.25N, which is different than the common antibixbyite (Zn3N4) and cubic (W2N) of its binary end members, and investigate the range of stability of these phases with composition fluctuation. Using the high-throughput method, 2”x2” samples were divided into 44 regions for analysis. The cation composition was analyzed at every region by x-ray fluorescence spectroscopy, then calibrated and analyzed for nitrogen by Rutherford backscattering on select samples. The structure was mapped according to composition by x-ray diffraction and Raman spectroscopy. The resistivity of various compositions was examined by four point probe. Optical transmission and reflection were measured to determine optical absorption and thickness for select samples.

Figure 1 (a) The wurtzite structure of the material predicted to be stable at Zn3WN4 or Zn0.75W0.25N. (b) X-ray diffraction pattern of the alloy at the composition Zn0.75W0.25N with overlaid simulated pattern for the predicted wurtzite structure. Invited: Investigation of Alloy Surface Oxidation using Ambient Pressure X-ray Photoelectron Spectroscopy

Gregory S. Herman Corresponding Author: greg.herman@oregonstate.edu School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, OR, 97331, USA Alloys are used for a wide variety of technologically important applications, including construction, aerospace, medical, automotive, electronic, and catalysis. Oxidation processes can be beneficial through the formation of a protective layer, or detrimental through poisoning of a surface. We have used ex-situ, in-situ, and ambient pressure X-ray photoelectron spectroscopy (XPS) to characterize the initial stages of oxidation for thin film alloy surfaces. We have found each method has benefits; however, we find that controlling both pressure and temperature during measurements allows more detail on preferential oxidation and surface enrichment. The focus of these experiments is to further the understanding of interfacial effects for electronic devices, catalysts for CO2 reduction, and corrosion resistant films.

Zn3WN4

Polyhedra Zn W

(a) (b)

32

References: [1] R.P. Oleksak, E.B. Hostetler, B.T. Flynn, J. McGlone, N.P. Landau, J.F. Wager, W.F. Stickle, G.S. Herman, Thin Solid Films 595 (2015) 209-213. [2] S. He, A.J. Pfau, J.T. Diulus, G.H. Albuquerque, G.S. Herman, Journal of Vacuum Science and Technology B (in press). [3] This work was performed, in part, at the Northwest Nanotechnology Infrastructure, a member of the National Nanotechnology Coordinated Infrastructure, which is supported by the National Science Foundation (Grant ECCS-1542101). Hydrogen Activation and Spillover on Single Palladium Atoms Supported on Fe3O4(001) Surface N. Doudin1, J.-Cheng Liu 2, M. D. Marcinkowski1, M.-T. Nguyen1, J. Li 2, V.-A. Glezakou1, G. Parkinson3, R. Rousseau1, Zdenek Dohnálek1 Nassar Doudin: nassar.doudin@pnnl.gov 1. Physical and Computational Sciences Directorate and Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, WA 99354, USA. 2. Department of Chemistry, Tsinghua University, Beijing 100084, China. 3. Institute of Applied Physics, Vienna University of Technology, 1040 Vienna, Austria Single-atom catalysts have recently attracted great attention due to their ultimate metal efficiency and the promise of novel properties. However, at the atomic level, little is known about their stability, interactions with the support, and mechanisms by which they operate. Recently it has been shown that on Fe3O4(001) surface, single metal atoms can be stabilized to temperatures as high as 700 K [1]. This high stability makes Fe3O4(001) a promising support for model studies of single atom catalysts. Here, we present a room-temperature study of H2 dissociation on single Pd atoms on Fe3O4(001) followed by H atom spillover via scanning tunneling microscopy (STM) and density functional theory (DFT). The exposure to H2 at 300 K results in the appearance of bright double protrusions located on surface iron (FeS) sites. Such protrusions were observed previously [2] following the adsorption of atomic H and hydroxyl formation (OSH) on bare Fe3O4(001). By analogy, we attribute the features observed here to OSH species. The DFT calculations further reveal that H2 dissociates heterolytically and spills over both hydrogen atoms onto Fe3O4(001). When the exposure to H2 is increased, the density of OSH’s is also observed to increase. With approximately every fourth surface oxygen atom hydroxylated, many areas show a local order with OSH’s spaced according to the (√2×√2)R45° surface reconstruction. STM data further indicate that H atoms diffusion is accelerated in the presence of coadsorbed water. At highest coverages of OSH’s (approximately every second oxygen atom hydroxylated), the reconstruction is lifted, and the Pd atoms become destabilized. These studies clearly demonstrate that single Pd atoms can efficiently dissociate H2 that spills over onto a reducible oxide support that can be extensively hydroxylated. [1] R. Bliem et al. Science 346, 6214 (2014). [2] G. S. Parkinson et al. Phys. Rev. B 82, 125413 (2010).

Phase imaging AFM to observe liquid phase heterogeneous hydrogenation in operando

Peter H. Pfromm1, Jared Carson2, Matthew Young2,*, Mary Rezac1, and Bruce Law3 Corresponding Author: peter.pfromm@wsu.edu 1. Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, USA 2. Department of Chemical Engineering and 3Department of Physics, Kansas State University, Manhattan, KS, USA *currently Park Systems, Boise, ID, USA It is challenging to observe events at the fluid/liquid interface during heterogeneous catalysis in operando. It will be demonstrated here that phase imaging atomic force microscopy (AFM) of the palladium surface of a catalytic membrane reactor (CMR) at atmospheric pressure and ambient temperature can detect the appearance/disappearance of hydrogen1, and chemical reactions in real time2. Mass transfer calculations and independent information on the physics of hydrogen/palladium interactions confirm the AFM observations. Recent unpublished results will be shown to demonstrate the observation of the hydrogenation of oxygen, and styrene over palladium in the liquid phase in real time and with the spatial resolution inherent to AFM. Phase imaging AFM allows real-time observation of heterogeneous catalytic reactions at the catalyst surface even in the liquid phase and with the exquisite spatial resolution inherent to AFM. This can currently not be matched by any other technique. References: [1] M. J. Young, P. H. Pfromm, M. E. Rezac and B. M. Law, Analysis of Atomic Force Microscopy Phase Data To Dynamically Detect Adsorbed Hydrogen under Ambient Conditions, Langmuir 40 (2014), 11906-11912. [2] M. Young, J. Carson, M. E. Rezac, B. Law, P. H. Pfromm, Atomic force phase imaging for dynamic detection of adsorbed hydrogen on a catalytic palladium surface under liquid, Ultramicroscopy 181 (2017), 42-49.

Figure 1 Real-time observation of H2 removal from a flat palladium surface using phase imaging AFM. (gas phase)

Initiate H2removalby N2 purge

Remainingstrongly bound H2vacates surface

0

30

60

Deg

rees

Phase angle

1µm

H2 vacating surface Raster

scan

270 s

0 s

34

Invited: Imaging and chemical probing of catalytic surface reactions with sub-nanoscale lateral resolution Norbert Kruse Corresponding Author: Norbert.Kruse@wsu.edu Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164, United States Catalytic reactions can be imaged with nanoscale resolution using video-field emission techniques. The advantage of this approach over common local-probe techniques is two-fold: first, a single nanosized metal grain can be imaged with atomic resolution all at once rather than by scanning and, second, the chemical composition can be probed in selected areas of this metal grain while imaging. The foundational principle of reactive imaging consists of using high electric fields thereby mimicking electrocatalytic conditions. Catalytic and electrocatalytic reactions are inherently non-linear and frequently involve surface reconstructions, which can be imaged with atomic resolution using Field Ion Microscopy (FIM). Reaction hysteresis may be observed and occasionally runs into very regular self-sustained oscillations. This will be demonstrated for the NO2 reduction with hydrogen on a Pt nanosized crystal using video-field electron microscopy [1]. The spatiotemporal dynamics of this oscillating reaction will be shown to be generated by chemical target patterns. The results exemplify that reaction-diffusion mechanisms hold at the nanoscale as they do at the macroscale. Next, we will inspect the catalytic water production from H2 and O2 on a nanosized Rh grain using FIM along with atom-probe techniques. Spatio-temporal patterns are observed which identify the catalytically active sites associated with water formation. Again, oscillatory behavior can occur. Combining the microscopic evidence with atom-probe techniques during the ongoing reaction allows determining the local chemical composition and, therefore, the feedback mechanism of the oscillations. Accordingly, a reversible surface oxidation is observed as evidenced by Rh-oxide field evaporation. Concurrent TEM observations confirmed precipitates of RhO2 are formed under (oscillatory) conditions of low water production. Spatio-temporal pattern formation and local chemical surface analysis were used to construct a microscopic model for the occurrence of rate oscillations [2]. The talk will be concluded by inspecting the future prospects of in-operando chemical probing with atomic scale lateral resolution. References: [1] C. Barroo, Y. De Decker, T. Visart de Bocarmé and N. Kruse, Emergence of Chemical Oscillations from Nanosized Target Patterns, Phys. Rev. Lett. 117 (2016) 144501 [2] ] J. S. McEwen, P. Gaspard, T. Visart de Bocarmé and N. Kruse, Nanometric Chemical Clocks, PNAS 106 (2009) 3006-3010

Understanding Solid Transformation of Akaganéite to Maghemite and Hematite by in situ Transmission Electron Microscopy

Xin Zhang1,⃰,⃰ Yang He2, Libor Kovarik2, Mark E. Bowden2, Yingge Du1, Lili Liu1, Chongmin Wang2, James J. De Yoreo1, Kevin M. Rosso1,⃰ ⃰ Corresponding Authors: xin.zhang@pnnl.gov and kevin.rosso@pnnl.gov 1 Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, USA 2 Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, USA Mineral phase transformation where primary particles are replaced by more stable phases is a common process in materials synthesis as well as in natural environmental settings where catalysts such as microorganisms drive phase changes. Besides being ubiquitous in soils and sediments, iron oxides and iron oxyhydroxides are widespread in technological applications such as energy devices, catalysis, microelectronics, coatings, pigments, gas sensors, and sorbents. Understanding the transformation mechanisms of iron oxides and iron oxyhydroxides is critical to designing novel materials and for predicting impacts of the iron cycle in nature. To probe atomic-scale pathways that underlie phase transformation and quantify the kinetic parameters controlling rates, we investigated solid phase transformation of β-ferric oxyhydroxide (β-FeOOH) nanowires, a common iron oxyhydroxide in chloride-containing environments, to anyhydrous iron oxide polymorphs via in situ heating transmission electron microscopy (TEM). Previous ex situ TEM studies found β-FeOOH solid nanowires transformed to hematite (α-Fe2O3) hollow nanowires after heating at 500 oC for 12 h via dehydration-recrystallization. Other studies such as in situ X-ray diffraction (XRD) concluded that the metastable phase maghemite (γ-Fe2O3) formed as a first intermediate phase during heating. In our work, in situ imaging of individual β-FeOOH nanowires in the TEM shows a new transformation mechanism. We observed the crystal structure of β-FeOOH first undergoes disordering upon heating to 200 oC to form an amorphous phase, and then the morphology changed from the solid nanowires to highly nanoporous nanowires composed of maghemite the grain size of which is inversely related to density of the pores. Phase outcomes strongly depend on the initial size of the β-FeOOH nanowires. For diameters smaller than 20 nm, the final product is maghemite; transformation of maghemite to hematite was not observed even upon heating to 500 oC for 12 h, which only eliminated the nanoporosity. In this case the final morphology of maghemite is solid nanowires, and high resolution TEM and STEM indicated these were oriented single crystals. For initial β-FeOOH nanowires with diameters larger than 20 nm, the final product depends on the heating temperature and time. Maghemite was the final product at transformation temperatures less than 300 oC, whereas hematite was the final product above 300 oC. The transformation of maghemite to hematite appeared to be by direct topotactic atomic rearrangement in the solid state; no intermediate amorphous phase was observed. Imaging was complemented by in situ XRD, in situ XPS and TGA-mass spectrometry measurements. In situ XRD showed amorphization of the β-FeOOH nanowires quickly upon approaching 200 oC and then maghemite was observed, consistent with the in situ TEM observation. However, the recalcitrance of maghemite conversion to hematite when starting from smaller β-FeOOH nanowires did not manifest in the XRD measurements upon increasing the heating temperature to 500 oC, which occurred readily for all different sized β-FeOOH nanowires. In this case ex situ TEM indicated the smaller β-FeOOH nanowires merged into larger particles, which allowed the maghemite to be readily transformed into hematite, for the XRD samples. For the in situ TEM experiments, because the β-FeOOH nanowires were mounted on a copper grid, this appeared to inhibit nanowire coalescence into larger particles during heating, allowing us to discover and

36

observe the size effect among individual nanowires. Both in situ XPS and TGA-MS measurements showed the loss of water and HCl upon heating. All in all, the solid phase transformation of β-FeOOH nanowires involves three steps: (i) dehydration of β-FeOOH nanowires to form a highly nanoporous amorphous intermediate; (ii) maghemite nucleation/crystallization; (iii) and topotactic phase transformation of maghemite to hematite, with a dependence on the initial particle size and heating temperature. The findings provide detailed new insights into processes controlling phase transformation outcomes in this system, and should help in the design new maghemite and hematite materials and in understanding processes controlling iron mineral transformations in the environment.

Thursday, June 21 - Surface Analysis ’18 Program

7:30 a.m. Light continental breakfast, registration, badging EMSL 1075/1077 Session III Special Session in Honor of Don Baer: Bio- and Nano- Materials

Moderator: Mark Engelhard, Pacific Northwest National Laboratory EMSL Auditorium

8:10 – 8:20 a.m. Opening Remarks and Medal to Don 8:20 – 9:00 a.m. Invited: The chameleon effect: Challenges to nanoparticle

preparation, characterization, and reproducible delivery Don Baer, Pacific Northwest National Laboratory

9:00 – 9:20 a.m. Monatomic and cluster argon ion XPS depth profiling of SrTiO3, HfO2

and Ta2O5

Paul Mack, Thermo Fisher Scientific 9:20 – 10:00 a.m. Invited: Fundamentals, state-of-the-art, and recent trends in

nanostructured materials for energy and electronic applications Luisa Whittaker-Brooks, University of Utah

10:00 – 10:30 a.m. Coffee Break: Vendor Exhibit and Refreshments EMSL 1075/1077 Special Session in Honor of Don Baer

Bio- and Nano- Materials Moderator: Luisa Whittaker-Brooks, University of Utah

EMSL Auditorium

10:30 – 11:10 a.m. Invited: Biomedical surface analysis with XPS and ToF-SIMS: Impact, advances & opportunities David G. Castner, University of Washington

11:10 – 11:30 a.m. In Situ infrared spectroelectrochemistry of precisely-selected ions using ion soft landing Venkateshkumar Prabhakaran, Pacific Northwest National Laboratory

11:30 – 11:50 a.m. Characterization of natural photonic crystals in glitterwing (chalcopteryx rutilans) damselfly wings using 3D TOF-SIMS and XPS Ashley A. Ellsworth, Physical Electronics Inc.

11:50 – 12:10 p.m. Photoactivated CVD of dimethyl(1,5-cyclooctadiene)platinum(II) on functionalized self-assembled monolayers Bryan Salazar, University of Texas at Dallas

12:10 – 1:30 p.m. Lunch EMSL 1075/1077 Session IV Phenomena on Model Surfaces and 2D Materials

Moderator: Líney Árnadóttir, Oregon State University EMSL Auditorium

1:30 – 2:10 p.m. Invited: 2D properties of WTe2, a layered topological semimetal David Cobden, University of Washington

2:10 – 2:30 p.m. Chemical bath deposition of substrate selective molybdenum disulfide Jenny K. Hedlund, University of Texas at Dallas

2:30 – 2:50 p.m. Elucidating the mechanism for the catalytic hydrodeoxygenation of phenols Jean-Sabin McEwen, Washington State University

2:50 – 3:20 p.m. Coffee Break: Vendor Exhibit and Refreshments EMSL 1075/1077

Phenomena on Model Surfaces and 2D Materials Moderator: Jean-Sabin McEwen, Washington State University

EMSL Auditorium

3:20 – 4:00 p.m. Invited: Two-dimensional silicates and phosphates, from structures to potential applications Eric Altman, Yale University

4:00 – 4:20 p.m. The effect of point defects on the interactions of Cl and α-Fe2O3 surfaces: The density functional theory study of the role of Cl in the depassivation process Qin Pang, Oregon State University

4:20 – 5:30 p.m. Undergraduate and General Poster Sessions EMSL Lobby

38

Shuttha Shutthanandan, Pacific Northwest National Laboratory 5:30 – 7:00 p.m. Dinner EMSL Bill’s Bistro 7:00 – 7:10 p.m. Poster Award Ceremony EMSL Auditorium 7:10 – 8:00 p.m. LIGO Presentation by Guest Speaker:

Jeff Kissel, LIGO Hanford Observatory 8:00 – 9:00 p.m. Career Panel Discussion

Bus Schedule:

Pickup location Tuesday Wednesday Thursday Friday Hampton Inn 7:00 am 7:00 am 7:00 am 7:00 am Red Lion Inn 7:15 am 7:15 am 7:15 am 7:15 am

EMSL 8:00 pm 8:00 pm 8:00 pm 1:15 pm EMSL 9:00 pm

Surface Analysis ‘18 Abstracts

Thursday, June 21 Invited: The Chameleon Effect: challenges to nanoparticle preparation, characterization, and reproducible delivery

Donald R Baer don.baer@pnnl.gov EMSL, Pacific Northwest National Laboratory, Richland WA, USA There is a growing awareness of reproducibility issues in many areas of science[1]. Due to inherent physical and chemical characteristics nanoparticles (NPs), which are of growing important in fundamental research, technological and medical applications, and environmental or toxicology studies, have multiple types of particle instabilities that make them susceptible to reproducibility challenges associated with their production, characterization and delivery. Inconsistencies and conflicts caused by non-reproducibility challenges have stimulated editorials and commentaries, scientific news items and journal articles. Dealing with the challenges is complicated by the multi- and cross-disciplinary nature of research and development associated with nano-objects which makes it difficult for many research teams to be knowledgeable about all of the important issues and to have the range of tools needed to address them. These processes and instabilities impact particles in multiple ways including: i) particle synthesis is can be complex and not easily reproducible and ii) particles are unstable, easily damaged and frequently change as a function of time or environment. My collaborators and I have summarized these two inter-related issues as: i) NPs are not (usually) created equal and ii) NPs are dynamic (like chameleons): they can change with time, handling and environmental conditions [2, 3]. As demonstrated for ceria and iron metal-core oxide shell NPs very slight changes in a process or environmental condition can cause particles to have unexpected behaviors after synthesis or at a later time. Consistent surface chemistry can also be difficult to achieve [4]. Such behaviors are significant causes of reproducibility and inconsistency issues in studies involving NPs. However, awareness of the dynamical potential of many NPs (the chameleon effect) and the challenges of providing consistent surface chemistry can help research teams identify problems and find ways to improve consistency[5]. The application of a well-defined and thought-out characterization plan, including some type of surface analysis, consistently applied at critical times, along with the collection and retention of provenance information (beyond that usually recorded or reported currently) can be useful tools to assist in addressing reproducibility issues or helping identify sources of possible variation. References: [1] R. Harris, Reproducibility issues, Chemical and Engineering News, 95 (2017) 2. [2] A.S. Karakoti, et al. Preparation and characterization challenges to understanding environmental and biological impacts of ceria nanoparticles, Surf. Interface Anal., 44 (2012) 882-889. [3] D.R. Baer, et al., Surface Characterization of Nanomaterials and Nanoparticles: important needs and challenging opportunities, Journal of Vacuum Science & Technology A, 31 (2013) 050820

40

[4] L.-K. Mireles, et al., Washing effect on superparamagnetic iron oxide nanoparticles, Data in Brief, 7 (2016) 1296-1301. [5] D.R. Baer, The Chameleon Effect: characterization challenges due to the variability of nanoparticles and their surfaces of nanoparticles and their surfaces, Frontiers in Chemistry, 6 (2018) 145. Monatomic and Cluster Argon Ion XPS Depth Profiling of SrTiO3, HfO2 and Ta2O5 Paul Mack1 and Mark Baker2, Corresponding Author: paul.mack@thermofisher.com 1) Thermo Fisher Scientific, The Birches Industrial Estate, East Grinstead, RH19 1 UB, UK 2) University of Surrey, Department of Mechanical Engineering Sciences, Guilford, GU2 7XH,

UK Thin metal oxide films are used in a wide variety of functional applications. There is, for example, interest in hafnium oxide (HfO2) and strontium titanate (SrTiO3) due to their particular band gaps and high dielectric constants. SrTiO3 has potential use in photocatalysis and energy storage and HfO2 is widely employed for optical coatings and optoelectronic device applications. Both materials are regularly deposited as thin films and doped to optimize their properties for the application. An accurate determination of thin film composition is paramount to the understanding and optimization of device performance. In this work, thin films of SrTiO3 and HfO2 have been deposited onto silicon substrates and XPS depth profiles have been performed through the thin films using both monatomic and cluster argon ion bombardment. Additionally, monatomic and argon cluster profiling of a 100nm Ta2O5 film grown on Ta was evaluated. The monatomic Ar+ profiles were performed using an incident ion energy of 500 eV or 1000eV and the gas cluster ion beam (MAGCIS) profiles were recorded using 8 keV Ar1000

+ and 8 keV Ar150

+ for SrTiO3 and HfO2 respectively. The Ta2O5 film was profiled with 6keV Ar1000

+ clusters. For HfO2 the optimum results were found when the MAGCIS ion beam was incident upon the sample at a glancing angle. These MAGCIS conditions yielded excellent retention of the original SrTiO3 and HfO2 stoichiometry during the profile, with no evidence of preferential sputtering or ion beam induced reduction. Using 500 eV Ar+, however, resulted in the preferential sputtering of oxygen leading to the presence of sub-oxide states in the XPS spectra of Ti in SrTiO3 and Hf and HfO2. The depth resolution was similar between the monatomic and cluster ion depth profiles for both thin film materials. Using the same incident ion beam angle, the etch rate for 8 keV Ar1000

+ was only 2.5 times lower than that for 500 eV Ar+. The results will be discussed in the light of known ion beam effects when sputtering metal oxide materials.

Invited: Fundamentals, state-of-the-art, and recent trends in nanostructured materials for energy and electronic applications Casey G. Hawkins1 and Luisa Whittaker-Brooks Corresponding Author: luisa.whittaker@utah.edu Department of Chemistry, University of Utah, 315 South 1400 East, Rm 2020, Salt Lake City, Utah 84112, United States

2D layered metal chalcogenides have displayed extraordinary properties that have put them on the forefront of various applications as promising catalysts, sensors, electrochromic devices, and electric actuators. Specifically, metal chalcogenides such as titanium (IV) sulfide (TiS2), has been identified as a promising low cost cathode for rechargeable batteries. TiS2 can exhibit specific capacities with a completely lithium-intercalated LixTiS2 (x = 1) as high as 238 mAhg-1. The electrochemical performance of bulk TiS2 cathodes has been hindered by its low ion diffusion coefficient and moderate electrical conductivity. To overcome these challenges, bulk TiS2 cathodes are mixed with conductive additives (typically carbon) and polymer binders (typically polyvinylidene fluoride -PVDF) to yield a paste

that is finally cast onto a current collector. However, the electrochemical performance of the electrode is lowered due to the extra weight of all the inactive components (i.e., additives, polymer binder, and metal substrates) introduced during the fabrication. An alternative to the use of pasted electrodes is the direct growth of well-defined nanostructures on a conducting substrate. In this talk, we will discuss the synthesis, characterization, and electrochemical performance of carbon- and binder-free cathodes comprising highly conducting TiS2 nanobelts. The short ion diffusion paths, high electrical conductivity and absence of materials that hinder ion migration such as carbon and PVDF have led to Li-ion and Na-ion batteries exhibiting high capacity, less capacity fade, and resilience under higher cycling rates. Moreover, key to developing new secondary battery systems is multielectron reactions involving more than one electron transfer, which may lead to higher specific capacity and energy density. Herein, we will discuss our recent findings towards rechargeable aluminum batteries comprising carbon- and binder-free TiS2 cathode electrodes. Finally, we will also discuss preliminary results that demonstrate high electrochemical performance of carbon- and binder-free TiS2 electrodes in all-solid state ion batteries.

42

Invited: Biomedical Surface Analysis with XPS and ToF-SIMS: Impact, Advances & Opportunities

David G. Castner Corresponding Author: castner@uw.edu National ESCA & Surface Analysis Center for Biomedical Problems, Departments of Bioengineering & Chemical Engineering, Box 351653, University of Washington, Seattle, WA 98195-1653 Biomedical surface analysis has undergone significant and numerous advances in the past 40 years in terms of improved instrumentation, introduction of new techniques, development of sophisticated data analysis methods, and the increasing complexity of samples analyzed. Comprehensive analysis of surfaces and surface immobilized biomolecules (peptides, proteins, DNA, etc.) with modern surface analysis instrumentation provides an unprecedented level of detail about the immobilization process and the structure of the immobilized biomolecules. Results from x-ray photoelectron spectroscopy (XPS or ESCA), time-of-flight secondary ion mass spectrometry (ToF-SIMS), near edge x-ray absorption fine structure (NEXAFS), surface plasmon resonance (SPR) and quartz-crystal microbalance with dissipation (QCM-D) biosensing, atomic force microscopy, and sum frequency generation (SFG) vibrational spectroscopy provide important information about the attachment, orientation, conformation, etc. of biomolecules. However, even with the advances that have been achieved with these powerful surface analysis techniques, there still remain many significant challenges for biomedical surface analysis. These include characterizing the surface chemistry and structure of nanoparticles, determining the structure of protein bound to surfaces, 3D imaging of cells and tissue sections, and maintaining biomolecules and materials in a biological relevant state when using ultra-high vacuum based analysis techniques. This talk will discuss the impact XPS and ToF-SIMS biomedical surface analysis has had, what the current challenges are, what is being done to address these challenges, and what some of the future opportunities are. Also discussed will be the role of well-defined standards to develop new biomedical surface analysis methods for characterizing more complex, biological relevant samples. In Situ Infrared Spectroelectrochemistry of Precisely-Selected Ions Using Ion Soft landing Venkateshkumar Prabhakaran1, Pei Su2, Grant E. Johnson1 and Julia Laskin2

Corresponding Author: venky@pnnl.gov 1. Pacific Northwest National Laboratory, Physical Sciences Division, Richland, Washington 99352 2. Department of Chemistry, Purdue University, West Lafayette, Indiana 47907 Understanding structural transformations of electroactive species at functioning electrode-electrolyte interfaces (EEIs) is essential for the rational design of high-performance solid-state systems for energy conversion and storage. In situ infrared (IR) spectroscopic characterization provides insight into structural changes of electroactive species at working interfaces. However, interpreting IR data can be challenging due to the poorly-defined nature of electrode interfaces prepared using conventional approaches. Ion soft-landing enables precisely-controlled deposition of mass- and charge-selected redox-active ions onto electrodes.(1-3) Herein, we describe our unique approach to simultaneously characterize the electrochemical activity and accompanying structural transformations of precisely-selected ions soft landed at EEIs. Our approach involves a

specially-designed three-electrode cell compatible with in situ infrared reflection absorption spectroscopy. A specially-designed thin nanoporous ionic liquid membrane is used as an electrolyte to prepare the cell. We studied the multielectron redox activity and related structural changes of mass-selected Keggin polyoxometalate anions. In situ cyclic voltammetry studies reveal the sequential multi electron transfer processes of soft-landed PW12O40

3- anions in a potential range of 0.3 V to -2.1 V. A distinct shift in the wavenumber of the IR absorbance of the terminal W=O band in the IRRAS spectra was observed during the multielectron reduction process. The experimental results demonstrate the feasibility of the in situ spectroelectrochemical approach for examining structural changes of well-defined electroactive species during electron transfer processes at solid-state EEIs. References: 1. V. Prabhakaran et al., Rational design of efficient electrode–electrolyte interfaces for solid-

state energy storage using ion soft landing. 7, 11399 (2016). 2. V. Prabhakaran, G. E. Johnson, B. Wang, J. Laskin, In situ solid-state electrochemistry of

mass-selected ions at well-defined electrode–electrolyte interfaces. Proceedings of the National Academy of Sciences 113, 13324-13329 (2016).

3. K. D. D. Gunaratne et al., Design and performance of a high-flux electrospray ionization source for ion soft landing. Analyst 140, 2957-2963 (2015).

Characterization of Natural Photonic Crystals in Glitterwing (Chalcopteryx rutilans) Damselfly Wings Using 3D TOF-SIMS and XPS

Ashley A. Ellsworth1, David M. Carr1, Gregory L. Fisher1, Benjamin W. Schmidt1,Wescley W. Valeriano2, Rodrigo R. de Andrade3, Juan P. Vasco2, Elizabeth R. da Silva4, Ângelo B. M. Machado5, Paulo S. S. Guimarães2, Wagner N. Rodrigues2,3 Corresponding Author: aellsworth@phi.com 1. Physical Electronics Inc., 18725 Lake Drive East, Chanhassen, MN 55317, USA 2. Departamento de Física, ICEx, UFMG, Av.Antônio Carlos 6627, 31270-901, B. H., MG, Brazil 3. Centro de Microscopia, UFMG, Av.Antônio Carlos 6627, 31270-901, B. H., MG, Brazil 4. Departamento de Morfologia, ICB, UFMG, Av.Antônio Carlos 6627, 31270-901, B. H., MG, Brazil 5. Departamento de Zoologia, ICB, UFMG, Av.Antônio Carlos 6627, 31270-901, B. H., MG, Brazil

The male Amazonian glitterwing (Chalcopteryx rutilans) damselfly has transparent anterior wings and brightly colored iridescent posterior wings. The colors are important for damselflies with regard to sexual recognition, mating, and territorial behavior. The source of the varying colors was examined by Valeriano [1] using electron microscopy and optical reflectance to analyze the internal microstructures. SEM and TEM images revealed that the iridescent wings have multiple alternating layers with different electronic densities. The variation of the local color was related to the number and thickness of the layers which varied across the wing. The colors span the visible spectrum with red, blue, and yellow/green regions on the wings. Measurement of the thickness and number of layers is readily achievable by electron microscopy; however; it was not possible to characterize the chemistry of the different layers giving rise to these natural photonic crystals.

44

TOF-SIMS is a well-established technique for analyzing the elemental and molecular chemistry of surfaces. TOF-SIMS can now be used to probe the 3D structure and chemistry of a wide variety of organic and inorganic materials, both synthetic and naturally occurring, due to the advent of cluster ion beams such as C60

+ and large Arn+ clusters. We will present results of 3D TOF-SIMS

analyses for both transparent and colored wings to correlate with the electron microscopy and optical microscopy to further the understanding of these natural photonic crystals. [2] Further, we will compare and contrast XPS large cluster Arn

+ depth profiling results to reveal the complementary nature of the two techniques.

Figure 1. Iridescent posterior wing from C. rutilans used for 3D TOF-SIMS and XPS analysis.

[1] W.W.Valeriano, Masters dissertation, UFMG, 2016. Retrieved from http://www.fisica.ufmg.br/posgrad/Dissertacoes_Mestrado/decada2010/wescley-valeriano/WescleyWalisonValeriano-diss.pdf.

[2] D. M. Carr, A. A. Ellsworth, G. L. Fisher, et al., Characterization of natural photonic crystals in iridescent wings of damselfly Chalcopteryx rutilans by FIB/SEM, TEM, and TOF-SIMS, Biointerphases 13 (2018), 03B406. Photoactivated CVD of Dimethyl(1,5-cyclooctadiene)platinum(II) on Functionalized Self-Assembled Monolayers

Bryan G. Salazar1, Hanwen Liu2, Lisa McElwee-White2 and Amy V. Walker1,3 Corresponding Author: amy.walker@utdallas.edu 1. University of Texas at Dallas, Dept. of Chemistry & Biochemistry, Richardson, TX, USA. 2. University of Florida, Dept. of Chemistry, Gainesville, FL, USA. 3. University of Texas at Dallas, Dept. of Materials Science & Engineering, Richardson, TX, USA. Chemical vapor deposition (CVD) is widely employed to deposit a variety of materials. However, CVD is generally unsuitable for use on organic substrates because it often requires high deposition temperatures (≥200˚C). Here an alternative to thermal activation, photolysis, is investigated for CVD processes on organic surfaces. We employ SAMs as model surfaces because they have a known uniform density of functional terminal groups and are synthetically flexible. In this study, the precursor used is dimethyl(1,5-cyclooctadiene)platinum(II) ((COD)Pt(CH3)2). To study the role of substrate chemistry on the CVD process, three different self-assembled monolayers (SAMs), carboxylic acid-, hydroxyl-, and methyl- terminated monolayers, were used. The resulting deposition was then investigated using time-of-flight secondary ion mass spectrometry (TOF SIMS) and X-ray photoelectron spectroscopy (XPS). The data indicates that the deposition is highly dependent on the wavelength and SAM terminal group. In agreement with previous

studies, the data also shows that the anionic polyhapto ligand, COD, is more difficult to remove than the alkyl ligand. Density functional theory (DFT) calculations provide insights into how the precursor decomposes and thus into the deposition mechanisms observed. These studies will therefore aid in the rational design for new precursors for photoactivated CVD on organic substrates. Invited: 2D properties of WTe2, a layered topological semimetal David Cobden Corresponding Author: cobden@uw.edu Department of Physics, University of Washington, Seattle WA 98195 Semimetals have recently received renewed attention for their various topological features. In devices fabricated from the layered topological semimetal WTe2 exfoliated down to monolayer thickness we have found a surprising range of phenomena, ranging from the quantum spin Hall effect to gated superconductivity and ferroelectricity. A Fermi surface is present down to the level of a bilayer, but not in a monolayer, where electron-hole correlations may dominate. Chemical Bath Deposition of Substrate Selective Molybdenum Disulfide

Jenny K. Hedlund1, and Amy V. Walker1,2 Corresponding Author: amy.walker@utdallas.edu 1. University of Texas at Dallas, Dept. of Chemistry & Biochemistry, Richardson, TX, USA. 2. University of Texas at Dallas, Dept. of Materials Science & Engineering, Richardson, TX, USA. Molybdenum disulfide (MoS2) thin films have been extensively studied due to the material’s tunable optical, mechanical, and electronic properties making it an ideal candidate for flexible nanoelectronics. While properties of few-layered MoS2 are well understood, controlled uniform growth of large-area MoS2 thin films remains a challenge. Chemical bath deposition (CBD) is a robust method used to grow thin films and nanostructures, and offers many advantages including low reaction temperatures (≤ 50°C), and flexible solution phase chemistry. In this work, CBD is employed to deposit large-area MoS2 thin films onto a variety of substrates ranging in surface chemistry and energy. SEM images show that polycrystalline flakes are grown on highly oriented pyrolytic graphite with an average diameter ~100 µm. Deposition of smooth thin films and crystallites were also deposited on sapphire and self-assembled monolayers with tailored terminal groups. XPS results confirm deposition of MoS2 as indicated by the Mo3d and S2s peaks present at the expected binding energy and peak ratios. Notably, layered MoS2 can be made as one of two different polymorphs, each of which possess distinct electronic properties. Bulk and synthesized MoS2 is commonly identified as the 2H polymorph, which maintains a trigonal prismatic geometry and behaves as a semiconductor with a band-gap energy ~1.2 eV. In contrast, MoS2 can also be synthesized with octahedral metal coordination geometry, known as the 1T polymorph, and consequently has semi-metallic properties. Using Raman spectroscopy measurements, we further demonstrate that the rate of deposition and film polymorph is dependent on the substrate surface chemistry.

46

Elucidating the Mechanism for the Catalytic Hydrodeoxygenation of Phenols

Neeru Chaudhary, Breanna Wong, Jake Bray, Alyssa Hensley, Yong Wang, and Jean-Sabin McEwen Corresponding Author: js.mcewen@wsu.edu Washington State University, The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Pullman, WA, USA. Quantifying the lateral interactions between adspecies is necessary in the development of truly predictive, theoretical models for bimetallic catalysts, as they will significantly affect the coverage and diffusion of adspecies and therefore the heterogeneous catalytic environment. To that end, we have characterized the benzene-benzene lateral interactions on a Pt (111) surface and a Pt3Sn (111) surface alloy. This coverage-dependent adsorption behavior was incorporated into a kinetic model for each surface and used to simulate the temperature-programmed desorption (TPD) spectra [1]. We found that a mean-field model is sufficient in describing the benzene-benzene lateral interactions. We also found that the adsorption of benzene was significantly weaker on the Pt3Sn (111) than on Pt (111), and as such, we were able to assign the monolayer desorption of benzene to a TPD peak previously attributed entirely to multilayer benzene desorption [1]. We also use density functional theory (DFT) to model the coverage dependent adsorption energetics of phenol on Pt (111). Several adsorption sites were tested that varied both the ring position and the functional group position over the surface, as shown in Figure 1a. Our results show that the phenol adsorption energy varies fairly linearly with the coverage for all the adsorption configurations (Figure 1b). From these adsorption energies, we then compute the average differential heat of adsorption, which agrees well with the corresponding experimental data, as shown in Figure 1c [2]. This comparison shows that we have accurately captured the coverage dependent adsorption energetics of phenol on Pt (111) within a mean-field model. Since a mean field model can also applied for the adsorption of benzene on Pt(111), this also indicates that such a mean field model can be extended to other aromatic molecules of interest. References: [1] C. Xu, Y.L. Tsai, B.E. Koel, Adsorption of cyclohexane and benzene on ordered tin/platinum (111) surface alloys, J. Phys. Chem., 98 (1994) 585-593. [2] S.J. Carey, W. Zhao, Z. Mao, C.T. Campbell, Energetics of Adsorbed Phenol on Ni(111) and Pt(111) by Calorimetry, The Journal of Physical Chemistry C (submitted), (2018). [3] The work at WSU was supported by the Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Biological Sciences and Geosciences (Award DE-SC-0014560).

Figure 1. Adsorption of phenol on Pt (111). (a) Most favorable adsorption sites. (b) Adsorption energy of phenol at each site as a function of coverage. (c) Comparison between the differential heat of adsorption as obtained in a mean field model and the experimental data.

Invited: Two-dimensional Silicates and Phosphates, From Structures to Potential Applications

C. Zhou1, X. Liang2, G.S. Hutchings3, A. Malashevich2, U.D. Schwarz1, S. Ismail-Beigi2 and E.I. Altman3 Corresponding Author: eric.altman@yale.edu 1. Department of Mechanical Engineering & Materials Science, Yale University, New Haven, CT USA. 2. Department of Applied Physics, Yale University, New Haven, CT USA. 3. Department of Chemical & Environmental Engineering, Yale University, New Haven, CT USA. There has been an explosion of interest in materials constructed of two-dimensional (2D) layers that interact with each other and their surroundings solely through van der Waals (VDW) interactions. Our focus has been on 2D VDW tetrahedral oxides with surfaces that resemble the catalytically relevant internal surfaces of zeolites while intrinsically featuring molecule-sized openings with the potential to serve as atomically thin membranes.[1-4] The parent member of this family of materials is SiO2 which forms 2D VDW bilayers constructed of mirror image planes of rings of corner-sharing SiO4 tetrahedra arranged in crystalline or amorphous structures. We have been using theory to guide a search for approaches to finely control the structure with the aims of replicating the structural diversity seen in three dimensions and of designing materials for efficient size-based separations. The results indicate that lattice strain and charge-balancing cations in 2D aluminosilicates can be viable routes to directing the structure of the materials.[5] Experimental results for 2D SiO2 growth on Pd(100) reinforce the former conclusion. To systematically apply strain epitaxial Ni-Pd alloy substrates with continuously tunable lattice constants were developed.[6] Growth on these alloys reveal a competition between 2D VDW SiO2 and a 2D Ni silicate. The 2D Ni silicate undergoes an abrupt phase transition at 1.3% tensile strain. We have also used theory to search for other materials that can adopt similar 2D VDW structures not seen in the bulk.[7] The most promising materials identified were AlPO4 and GaPO4. The results reveal general guidelines based on ionic size and bulk phase diagrams that favor 2D tetrahedral oxide growth. Meanwhile, 2D GaPO4 displays tetrahedral rotations that create pores that can expand to allow small molecules to pass through and contract to become impermeable as tensile strain is applied and removed. Based on these findings a pressure-driven molecular aperture is proposed.

Figure 1 (a) Computed energy to form 2D VDW TT’O4 structures from the favored bulk materials plotted as a function of the average crystal radii of the tetrahedral cations. (b, c) Structures of 2D VDW AlPO4 (b) and GaPO4 (c) with red, yellow magenta and green reflecting O, P, Al, and Ga atoms. The alternating tetrahedral rotations in GaPO4 allow Ga-O-P bond

48

angles to match the angles favored in the bulk structure. (d) Plot of the openings in the AlPO4 and GaPO4 structures plotted as a function of strain. The effect is large in GaPO4 because the material responds to strain by the tetrahedra rotating, thereby opening and closing the pores. References: [1] L. Lichtenstein, M. Heyde, and H.-J. Freund, J. Phys. Chem. C 116, 20426 (2012). [2] M. Heyde, S. Shaikhutdinov, and H. J. Freund, Chem. Phys. Lett. 550, 1 (2012). [3] E. I. Altman, J. Götzen, N. Samudrala, and U. D. Schwarz, J. Phys. Chem. C 117, 26144

(2013). [4] E. I. Altman and U. D. Schwarz, Adv. Mater. Interfaces 1, 1400108 (2014). [5] A. Malashevich, S. Ismail-Beigi, and E. I. Altman, J. Phys. Chem. C 120, 26770 (2016). [6] G. S. Hutchings, J.-H. Jhang, C. Zhou, D. Hynek, U. D. Schwarz, and E. I. Altman, ACS

Appl. Mater. Interfaces 9, 11266 (2017). [7] E. I. Altman, J. Phys. Chem. C 121, 16328 (2017).

The effect of point defects on the interactions of Cl and α-Fe2O3 surfaces: The density functional theory study of the role of Cl in the depassivation process

Qin Pang1, Hossein DorMohammadi2, O. Burkan Isgor2, Líney Árnadóttir1 Corresponding Author: pangq@oregonstate.edu 1. School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR, 97331, United States 2. School of Civil and Construction Engineering, Oregon State University, Corvallis, OR, 97331, United States Experimental studies have shown that the protective iron passive film formed in highly alkaline environments, such as inside reinforced concrete, can be depassivated by Cl ions under the same condition. Several hypotheses have been proposed to explain the role of Cl in the depassivation, such as ion exchange model and point defect model, but the atomistic mechanism of depassivation is still not fully understood. Hematite (α-Fe2O3), a Fe (III) rich oxide, is used in this study to represent the outer layer of the passive film. Density functional theory (DFT+U) calculations of Cl interactions with α-Fe2O3 (0001) are used to investigate the feasibility of the two hypotheses of Cl-induced depassivation and the role of defects. Three surface point defects are considered, Fe vacancy, O vacancy and Fe-O pair vacancies. Results suggest that the O vacancies enhance, and the Fe vacancies weaken the adsorption of Cl, but the point defects show no clear effect on the structural changes caused by the adsorption. The insertion energy of Cl into the subsurface is endothermic indicating that the subsurface Cl is not thermodynamically favorable. The structural changes caused by the subsurface Cl shows no evidence that the subsurface Cl causes surface breakdown. These results do not support the hypothesis of the ion exchange model. In the investigation of point defect model, the calculation of the Fe vacancy formation energy shows that the adsorbed Cl can assist in the surface Fe vacancy formation. Comparison of the stability of the two vacancies (Fe and O vacancy) in the subsurface shows that Fe vacancy is energetically more favorable in the deeper subsurface while O vacancy

prefers to stay in the layers closer to the surface. The adsorbed Cl can affect the two diffusion processes by making the two processes more energetically favorable. These are consistent with the hypothesis presented in the point defect model. This study suggests that the point defect model is the more promising model to explain the Cl-induced depassivation process.

50

Friday, June 22- Surface Analysis ’18 Program

7:30 a.m. Light continental breakfast EMSL 1075/1077 Session V Energy Materials

Moderator: Martin McBriarty, Pacific Northwest National Laboratory EMSL Auditorium

8:20 – 9:00 a.m. Invited: Electrochemical materials and interface studies for improved activity and durability in chemical transformation processes Yuyan Shao, Pacific Northwest National Laboratory

9:00 – 9:20 a.m. Operando investigation of complex electrochemical processes occurring at electrode-electrolyte interfaces at the molecular level Zihua Zhu, Pacific Northwest National Laboratory

9:20 – 9:40 a.m. Resilient high temperature UHV sealing Chad Thomas, Technetics Group

9:40 – 10:00 a.m. Understanding nanorod dissolution mechanisms by liquid phase electron microscopy: The case of β-FeOOH Lili Liu, Pacific Northwest National Laboratory

10:00 – 10:20 a.m. Anodically grown nanoporous Nb2O5: Preparation and properties Pete Barnes, Boise State University

10:20 – 10:40 a.m. Break: Refreshments EMSL 1075/1077 Energy Materials

Moderator: Zihua Zhu, Pacific Northwest National Laboratory EMSL Auditorium

10:40 – 11:20 a.m. Invited: In situ chemical imaging of electrochemical interfaces Vijayakumar Murugesan, Pacific Northwest National Laboratory

11:20 – 11:40 a.m. Precursor-derived silicon carbide based materials for MHD power generation: Thermionic emission behavior YiHsun Yang, University of Washington

11:40 – 12:00 p.m. Structure and electrochemical response of the hematite-electrolyte interface Martin McBriarty, Pacific Northwest National Laboratory

12:00 – 12:10 p.m. Closing Remarks 12:10 – 12:30 p.m. Box Lunch to go EMSL 1075/1077 12:20 – 1:00 p.m. PNWAVS Board of Directors Meeting EMSL 1075/1077 1:00 – 2:30 p.m. EMSL Tours

Note: must be badged and wear close-toed shoes EMSL Lobby

Bus Schedule:

Pickup location Tuesday Wednesday Thursday Friday Hampton Inn 7:00 am 7:00 am 7:00 am 7:00 am Red Lion Inn 7:15 am 7:15 am 7:15 am 7:15 am

EMSL 8:00 pm 8:00 pm 8:00 pm 1:15 pm EMSL 9:00 pm

Surface Analysis ‘18 Abstracts

Friday, June 22 Invited: Electrochemical materials and interface studies for improved activity and durability in chemical transformation processes. Yuyan Shao Pacific Northwest National Laboratory Corresponding Author: Yuyan.shao@pnnl.gov Chemical transformations provide energy, fuel and chemicals for today’s society, therefore its importance cannot be overestimated. Electrochemistry offers the possibility to drive chemical transformations under ambient temperature and pressure. More importantly, the interconversion of chemical and electrical energy by electrochemical means (e.g., electrocatalysis) of using the electron potential to control the directions and rates of chemical processes provides a flexible and scalable solution to store energy in chemical bonds and retrieve this energy wherever and whenever needed. The so-called water cycle (2H2+O2↔2H2O) is the most intensively investigated one. One of the grand technical challenges is to find active and durable electrode materials without much resource strain that can do the chemical transformation jobs. In this talk, we will discuss our recent progress on developing electrocatalysts for hydrogen and oxygen. We will emphasize how the surface structure drives hydrogen evolution, how the catalyst structure evolves under (electro)chemical stressing and how they affect the performance. We will also highlight our new progress on developing platinum group metal (PGM)-free electrocatalysts for fuel cell applications. Operando Investigation of Complex Electrochemical Processes Occurring at Electrode-Electrolyte Interfaces at the Molecular Level

Zihua Zhu1* and Xiao-Ying Yu2 Corresponding Author: zihua.zhu@pnnl.gov 1. W. R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354 USA 2. Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99354 USA

Electrochemistry has gained increasing interest in recent decades. However, mechanisms of many important electrochemical reactions are still under debate, due to lack of desirable analytical tools that can examine electrode-electrolyte interfaces at the molecular level under operation conditions. During the last several years, we developed the in situ liquid secondary ion mass spectrometry (SIMS) technique and applied it on operando characterization of electrochemical processes at electrode-electrolyte interfaces1. In this presentation, design and fabrication of vacuum compatible electrochemical cells for in situ liquid SIMS analysis will be briefly discussed and an interesting application about molecular characterization of formation and dynamics of electric double layer2 will be introduced. In addition, our recent results showed unexpected low fragmentation of interesting molecules during in situ SIMS analysis3 and solvation of ions in various solutions could

52

be investigated4. Therefore, the development of in situ liquid SIMS opens a new door to investigate complex electrochemical processes occurring at electrode-electrolyte interfaces.

1 Liu, B. W. et al. In situ chemical probing of the electrode-electrolyte interface by ToF-SIMS. Lab Chip 14, 855-859, doi:10.1039/c3lc50971k (2014).

2 Wang, Z. Y. et al. In Situ Mass Spectrometric Monitoring of the Dynamic Electrochemical Process at the Electrode-Electrolyte Interface: a SIMS Approach. Anal Chem 89, 960-965, doi:10.1021/acs.analchem.6b04189 (2017).

3 Yu, X. F. et al. An investigation of the beam damage effect on in situ liquid secondary ion mass spectrometry analysis. Rapid Commun Mass Sp 31, 2035-2042, doi:10.1002/rcm.7983 (2017).

4 Zhang, Y. Y. et al. Investigation of Ion-Solvent Interactions in Nonaqueous Electrolytes Using in situ Liquid SIMS. Anal Chem 90, 3341-3348 (2018).

Resilient High Temperature UHV Sealing

Chad Thomas1, Ryan McCall2 Corresponding Author: chad.thomas@technetics.com, ryan.mccall@technetics.com 1. Technetics Group, Columbia, USA 2. Technetics Group, Columbia, USA Ultra-High Vacuum applications typically require all metal sealing due to outgassing and permeation concerns. Many of these systems are baked at a high temperature in order to reach the lowest base pressure and required cleanliness levels. However, high temperature bake outs can be problematic for traditional metals seals due to thermal expansion and the occasional need to have a shaped or non-circular configuration. Other critical sealing applications such as etching or thin film deposition also require a metal seal that has low outgassing and permeability – but must also be compatible with the process gasses or plasma. This presentation will discuss a unique type of metal seal that utilizes a helical wound spring with layered metal jackets to address these issues. Presentation topics will include the metal-to-metal sealing concept along with design factors such as seating load, seal function, seal material selection, leak rate, and required seating load, groove configuration and finish.

Understanding nanorod dissolution mechanisms by liquid phase electron microscopy: The case of β-FeOOH Lili Liu,1 Xin Zhang,1 Elias Nakouzi,1 Libor Kovarik,2 Jennifer Soltis,1 Kevin Rosso1 and James J De Yoreo 1, 3 Corresponding Author: James.DeYoreo@pnnl.gov 1. Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States. 2. Environmental Molecular Sciences Laboratory Pacific Northwest National Laboratory, Richland, Washington 99354, United States. 3. Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98185, United States. Nanoparticle dissolution is a common process in synthetic procedures where primary particles are replaced by more stable phases, as well as in environmental settings where they both serve as electron sinks or sources for microbes and are responsible for release of nutrients or contaminants. Iron oxides and iron oxyhydroxides, which are widespread in technological applications and environmental settings, are a prime example. To decipher the pathways that underlie dissolution and quantify the kinetic parameters controlling rates, we investigated dissolution of β-ferric oxyhydroxide (β-FeOOH) nanorods via in situ liquid phase (LP)-TEM. Previous ex situ studies that investigated dissolution of iron (III) hydroxides by proton or photoreductive attack found that photoreductive dissolution of is faster than by nonreductive dissolution (e.g. proton-promoted or ligand promoted thermal dissolution). Other studies concluded that the rate-determining step during dissolution in HCl is protonation of the surface together with formation of a chloride-Fe surface complex. Generally, dissolution of β-FeOOH nanorods in strong acids occurs end-to-end along the [010] direction and has been attributed to proton penetration and destabilization of so-called “tunnel structures” by removal of Cl ions. In our work, we find dissolution of β-FeOOH nanorods occurs both end-to-end (along [010]) and side-to-side (along [100]) directions under the electron beam, even at extremely low electron dose rates. Dissolution involves two reaction steps: (i) beam radiolysis of the water to release H+ that promotes end-to-end dissolution; (ii) beam induced reduction of Fe(III) at the nanorod surface with subsequent release of Fe(II) into the solution, which drives side-to-side dissolution. To further understand the role of protons on dissolution, we investigated the effect of pH. The results show low concentration pH buffers reduce and even stop end-to-end dissolution, but side-to-side dissolution was still observed, leading to formation of dumbbell-shaped nanopartcles that eventually dissolve completely. Nanorods dissolution was totally inhibited for pH buffer concentrations higher than 100 mM. In addition, we found that chloride ions can inhibit end-to-end dissolution of β–FeOOH nanorods while promoting side-to-side dissolution at low concentration pH. The results provide strong evidence that radiolysis contributes to the reduction of Fe(III) to release of Fe(II) even at neutral pH, thus promoting dissolution of iron oxyhydroxides. Because, photolysis is a naturally occurring process in the environment that is similar to radiolysis, the findings of this in situ study may help to understand dissolution and transformation of iron oxides and iron oxyhydroxides in Nature.

54

Anodically Grown Nanoporous Nb2O5: Preparation and Properties

Pete Barnes, Kiev Dixon, Laura Rill, Devan Karsann, and Claire Xiong Corresponding Author: clairexiong@boisestate.edu Micron School of Material Science and Engineering, Boise State University, 1910 University Drive, Boise, ID 83725, United States Lithium-ion batteries (LIB) are the leading technology in energy storage systems for applications such as electric vehicles and electrical grids, however, there are still considerable limitation including safety and stability. Next generation electrodes need to accommodate charge in a faster, more reliable, and highly reversible manner. One way to approach these concerns is to design nanostructured metal oxides, which have higher potentials for safe operation, while maintaining high reversible capacity. When compared to the commonly used graphite, metal oxides provide a chemically inert anode with lithiation voltages well above that of Li plating and side reactions with electrolyte. While bulk oxides suffer from low conductivity, by nanostructuring the oxide we can enhance the performance of batteries by facilitating fast electron- and ion-transport. One material yet to be fully researched by the battery community is nanostructured niobium oxides (Nb2O5). Schmuki et al. (2012) modified the anodization of Ta, pioneered by Melody et al. (1998), to produce the first ordered nanostructured Nb2O5 [1, 2], which has promising intercalation behavior as a LIB electrode. However, the formation of a uniform oxide layer is still challenging. A critical parameter to control is the substrate surface roughness. Recent work shows that it is possible to obtain surfaces with sub nm roughness using an acid-methanol electrolyte at low temperature [3]. This electropolishing process employs a fluoride-free electrolyte of sulfuric acid and methanol at low temperature (−70°C) to provide high quality macro- and micro-smoothing of the metal surface. Polished Nb metal resulted in uniform and even nanopore growth across the surface of the substrate during anodic treatment. This lends experimental control over the pore diameter and length of channels. Presented are the methods of forming these channels, controlling the nanoarchitecture, and discussing their properties.

Figure 1 (a) Surface pores of nanochanneled niobium oxide. (b-c) Side profile of nanochannels. References: [1] B. Melody, T. Kinard, P. Lessner, The non-thickness-limited growth of anodic oxide films on valve metals, Electrochem Solid St, 1 (1998) 126-129. [2] K. Lee, Y. Yang, M. Yang, P. Schmuki, Formation of Highly Ordered Nanochannel Nb Oxide by Self-Organizing Anodization, Chem-Eur J, 18 (2012) 9521-9524. [3] P. Barnes, A. Savva, K. Dixon, H. Bull, L. Rill, D. Karsann, S. Croft, J. Schimpf, H. Xiong, Electropolishing valve metals with a sulfuric acid-methanol electrolyte at low temperature, Surface and Coatings Technology.

Invited: In situ chemical imaging of electrochemical interfaces

Vijay Murugesan1*, Kee Sung Han1,2, Vaithiyalingam Shutthanandan2, Suntharampillai Thevuthasan2 and Karl T. Mueller1 Corresponding Author: vijay@pnnl.gov 1 Joint Center for Energy Storage Research (JCESR), Pacific Northwest National Laboratory, Richland, Washington 99352, United States. 2 Environmental and Molecular Science Laboratory (EMSL), Pacific Northwest National Laboratory, Richland, Washington 99352, United States. Electrochemical processes at electrode-electrolyte interfaces has wide span, both spatially—ranging from one-tenth of a nanometer up to one-hundred nanometers—and temporally—lasting from nanosecond up to a few minutes. The challenge is to detect, identify and quantify the transient species/structures, which dictates the spatial and temporal evolution of electrochemical processes. Often, these transient species and associated reaction pathways are inaccessible by any single spectroscopic and/or classical computational methods1-4. Gaining an in-depth understanding about these interfacial process under realistic electrochemical conditions requires multi-modal probes that integrate theoretical computation methods with multiple analytical methods having the necessary spatial and temporal resolution. Joint Center for Energy Storage Research (JCESR) an energy innovation hub, has brought together a wide range of characterization capabilities into a focused, multi-modal characterization protocol through inter-laboratory collaboration that will enhance the accessing the wide span regions of electrochemical processes. In this presentation, we will discuss the recent developments related to in situ multimodal approaches that can provide unprecedented chemical imaging of these complex interfaces5. In particular, our recent in-situ X-ray photoelectron spectroscopy (XPS) analysis which yielded an unparalleled view of the chemical speciation and microscopic evolution of the SEI layer will be discussed (see Figure 1).

Figure 1. (a) The schematic diagram of the sample holder developed for battery cycling and in-situ XPS characterization. (b) The distribution of different chemical species on the Li anode is shown between charge and discharge cycles (see Ref.5) References: 1. J. Chen, K. S. Han, W. A. Henderson, K. C. Lau, M. Vijayakumar, T. Dzwiniel, H. Pan, L. A. Curtiss, J. Xiao and K. T. Mueller, Advanced Energy Materials 6 (11) (2016). 2. H. Pan, K. S. Han, M. Vijayakumar, J. Xiao, R. Cao, J. Chen, J. Zhang, K. T. Mueller, Y. Shao and J. Liu, ACS Applied Materials & Interfaces 9 (5), 4290-4295 (2017). 3. N. N. Rajput, V. Murugesan, Y. Shin, K. S. Han, K. C. Lau, J. Chen, J. Liu, L. A. Curtiss, K. T. Mueller and K. A. Persson, Chemistry of Materials 29 (8), 3375-3379 (2017).

56

4. M. Vijayakumar, N. Govind, E. Walter, S. D. Burton, A. Shukla, A. Devaraj, J. Xiao, J. Liu, C. Wang, A. Karim and S. Thevuthasan, Physical Chemistry Chemical Physics 16 (22), 10923-10932 (2014). 5. M. I. Nandasiri, L. E. Camacho-Forero, A. M. Schwarz, V. Shutthanandan, S. Thevuthasan, P. B. Balbuena, K. T. Mueller and V. Murugesan, Chemistry of Materials 29 (11), 4728-4737 (2017). Precursor-derived silicon carbide based materials for MHD power generation: thermionic emission behavior

YiHsun Yang1, Marjorie Olmstead2, and Fumio S. Ohuchi1 Corresponding Author: yyh1982@uw.edu 1. Materials Science and Engineering, University of Washington, Seattle, USA 2. Physics, University of Washington, Seattle, USA Direct energy extraction convert thermal energy to electrical energy directly. Our research is to make the best use of current fossil fuels by providing an alternative option: MagnetoHydroDynamics (MHD) power generation. Direct power extraction via MHD principles offers a potential step improvement in thermal efficiencies over energy systems utilizing traditional turbamachinery. While MHD power generation drawn huge attentions from researches in the 60s, but the focus has been shifted to other interests due to material issues. While there are several advantages for MHD power generation, it is the technique strictly relies on high temperature materials. In particular, one of the weakness of the current technology is the durability of the current collectors on the walls of the generator (channel electrodes) [1]. The channel electrode materials must withstand extreme high temperature and complicated chemicals including seeds and coal slag depending on the combustion type. As the technology advance, the preferred combustion method is no long high sulfur contain coal combustion but potassium seeded oxy-fuel combustion. [2] The change of fuel drastically reduced the requirement for the channel electrode materials and thus an opportunity opened up for researchers. We developed a novel class of SiC-based ceramic composite materials through a polymer-precursor-derived route with tailored compositions for channel applications in magnetohydrodynamic (MHD) generators. As the MHD channel electrodes requiring such high temperature to operate, researchers must gauge the materials functionality versus stability. In the presenting SiC/C system, a thorough characterization has been done including: Structural, morphological, and elemental data were obtained and analyzed. XRD was used for structure analysis; SEM was for morphologic analysis; XPS and GDOES was used for elemental analysis; 29Si NMR provided bulk silicon chemical state; Raman spectra provided further information on carbon species. Once confirmed continuous evolving surface with in-situ Auger electron spectroscopy (AES) couple with thermionic emission, an alternative method, thermionic emission energy distribution (TEED) technique has been developed to decipher the materials work function at desired temperature. Previously, we have reported the method utilizing Richardson Dushman equation to extract work function at certain temperature range. In the present report, instead of temperature range, work function at certain temperature can be evaluated with TEED technique. A successful outcome of this research will result not only in the emergence of reliable and

affordable designed materials for MHD applications but also suitable for any other future material exploratory. References: [1] V. K. Rohatgi, Bull. Mater. Sci. 6, 71 (1984). [2] R. C. Woodside, (2017). Structure and electrochemical response of the hematite-electrolyte interface

Martin E. McBriarty1, Joanne E. Stubbs2, Guido F. von Rudorff3, Jochen Blumberger3, Peter J. Eng2, Kevin M. Rosso1 Corresponding Author: Martin E. McBriarty (memcbr@gmail.com) 1. Physical Sciences Division, Pacific Northwest National Laboratory, Richland, WA, USA 2. Center for Advanced Radiation Sources, University of Chicago, Chicago, IL, USA 3. Department of Physics and Astronomy, University College London, London, UK The interfaces between transition metal oxides (TMOs) and aqueous electrolytes regulate geochemical transformations and (photo)electrocatalysis. Atomically precise measurements of TMO-electrolyte interfaces under appropriate working conditions are required for the development of accurate models of interfacial reactions. We present detailed measurements of the reactive and chemically complex hematite (α-Fe2O3) (1-102) surface in electrolyte (5 mM Na2SO4, pH 7.4 and pH 4.0) at open circuit conditions and under applied cathodic bias. Interface structures are measured in situ by synchrotron X-ray crystal truncation rod (CTR) scattering using a novel electrochemical mini-cell, and CTR results are interpreted in light of first-principles molecular dynamics simulations. The equilibrium structure of this hematite-electrolyte interface at circumneutral pH is defined by the exchange of water molecules between terminal aquo ligands and solution with picosecond frequency, resulting in a steady-state partial coverage of potentially reactive surface iron sites.1 Under cathodic bias, the surface is excessively protonated, strengthening the near-surface hydrogen-bonding network and armoring the electrode against reductive dissolution (Figure 1).2 At pH 4.0, the interfacial water ordering is weaker, and the surface iron stoichiometry changes with applied bias. These results reveal the fine details of the electrical double layer at a complex TMO-electrolyte interface and motivate further in situ characterization of these interfaces during electrocatalytic reactions.

Figure 1 At circumneutral pH, the interface between hematite (1-102) and dilute aqueous solution is defined by frequent water exchange between terminal aquo ligands and solvent. Under cathodic bias, interfacial water rearranges, protecting the surface against reductive dissolution.

α-Fe2O3(OCP)

α-Fe2O3(cathodic bias)

58

References: [1] M.E. McBriarty, G.F. von Rudorff, J.E. Stubbs, P.J. Eng, J. Blumberger, and K.M. Rosso, “Dynamic Stabilization of Metal Oxide-Water Interfaces”, J. Am. Chem. Soc. 139 (2017) 2581-2584. [2] M.E. McBriarty, J.E. Stubbs, P.J. Eng, and K.M. Rosso, “Potential-Specific Structure at the Hematite-Electrolyte Interface”, Adv. Funct. Mater. 28 (2018), 1705618.

Poster Session - Wednesday, June 20 - Surface Analysis ’18

Poster Number

Title and Presenter Note

1 Nanoscale characterization of engineered articular cartilage using atomic force microscopy Mahmoud Amr, Washington State University

Graduate

2 New benchtop XES for phosphorus and sulfur characterization William M. Holden, University of Washington

Graduate

3 Synchrotron near ambient pressure -XPS study of the inhibition of active sites in iron-nitrogen-carbon electrocatalyst for oxygen reduction reaction Yechuan Chen, University of Mexico

Graduate

4 Theoretical study of the decarboxylation and decarbonylation of acetic acid over Pd (111) Kingsley Chukwu, Oregon State University

Graduate

5

High resolution multimodal compositional characterization of nanocrystalline soft magnetic materials Trevor Clark, Pacific Northwest National Laboratory

Graduate

6 Comparative analysis of surface configurations of CO adsorbed on hcp and fcc cobalt for the fischer-tropsch synthesis Greg Collinge, Washington State University

Graduate

7 Influence of ambient conditions on Inorganic EUV photoresist radiation induced chemistries studied using ambient pressure x-ray photoelectron spectroscopy J. Trey Diulus, Oregon State University

Graduate

8 The study of the energetics and geometries of dodecaborate complexes and polysulfide clusters with photoelectron spectroscopy and theoretical calculations Zhipeng Li, Pacific Northwest National Laboratory

Graduate

9 Molecular examination of ion solvation using in situ liquid SIMS Wen Liu, China University of Geosciences

Graduate

10 Low temperature nanopatterning on graphite via carbon gasification reaction using cobalt oxides Carlos Morales Sanchez, Universidad Autonoma de Madrid, Spain

Graduate

11 Accounting for beam driven damage events of soft materials within liquid cell transmission electron microscopy experiments Trevor Moser, Pacific Northwest National Laboratory

Graduate

12 Surface x-ray diffraction study of interfacial conduction in complex metal oxides Widitha Samarakoon, Oregon State University

Graduate

13 An investigation of solvent effects in the decomposition of acetic acid using density functional theory and ambient pressure x-ray photoelectron spectroscopy Sean Seekins, Oregon State University

Graduate

14 The role of the -OH groups of (hydroxyethyl) methacrylate (HEMA) on KGF conformational dyna.m.ics at the surface of HEMA-based hydrogels Shohini Sen-Britain, State University of New York at Buffalo, NY

Graduate

15 A macro-scale and solution-based approach towards a mixed semi-conducting and organically functionalized surface Yi Zhang, Washington State University

Graduate

16 The effect of irradiation on TiO2 for lithium ion batteries Kassiopeia Smith, Boise State University

Graduate

17 Synthesis of Mg-MOF-74 thin film and potential CO2 sensing application Hao Sun, Oregon State University

Graduate

18 In situ studies of electrocatalyst for oxygen evolution reaction in acidic condition using a combination of x-ray scattering and spectroscopy Maoyu Wang, Oregon State University

Graduate

60

19 Localized surface plasmon resonance enhanced carbon dioxide gas sensing based on nanostructured covellite copper sulfide thin film Yujing Zhang, Oregon State University

Graduate

20 A graphene-based ambipolar vacuum transistors Gongtao Wu, Peking University

Graduate

21 Lab-based XAFS and XES for materials chemistry research Evan Jahrman, University of Washington

Graduate

Surface Analysis ‘18 Poster Abstracts

Wednesday, June 20

Nanoscale characterization of engineered articular cartilage using atomic force microscopy

M. Amr, A. Mallah, H. Abusharkh, C. Quisenberry, A. Nazempour, B. J. Van Wie, N. I. Abu-Lail

Corresponding Author: mahmoud.amr@wsu.edu Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA. Articular cartilage (AC) is a tissue that lubricates moving joints, providing ease of movement and acts in a load-bearing joint capacity. AC is a low cellular density tissue that is avascular and aneural, which limits its ability to heal and prevents the feeling of discomfort until severe damage has already occurred. Osteoarthritis (OA) is a degenerative disease that is characterized by the inflammation of AC that can be caused by many factors such as injury and genetics. OA is one of the leading causes of disability in the U.S. and worldwide, more than 54 million adults have been diagnosed with OA in the US, and that number is estimated to reach more than 70 million by the year 2040. Current treatments include painkillers, hyaluronic acid injections, and invasive total knee replacement surgeries. These treatments only provide temporary relief and only useful in treating symptoms but not the cause of the disease. As such, finding alternative approaches to help people with OA is crucial, and one of these approaches is tissue engineering. Tissue engineering involves the creation of tissues in vitro by combining a cell source, a scaffold and growth factors in a bioreactor that represents the in vivo microenvironment. When combined, a mechanically sound AC tissue that has native-mimicking ability both structurally and functionally. The engineered tissue is characterized quantitatively using biochemical analyses for the two main markers of a healthy tissue, total glycosaminoglycan (GAG) and collagen. Furthermore, these markers are qualitatively characterized using histological techniques. In addition, gene expression using real-time quantitative polymerase chain reaction (RT-qPCR) is performed to quantify key chondrogenic, osteogenic, adipogenic and fibrogenic markers. All of these can provide qualitative and quantitative assessments of the biochemical content of the tissue but fail to describe AC tissue functionality. A unique tool that can be utilized to assess AC function is atomic force microscopy (AFM). AFM provides the ability to study the structure-function relationship at the nanoscale level where information is gathered by “feeling” the surface with a mechanical probe or cantilever and through micro-indentations on the surface to quantify forces and elasticity. In our study, we have created an engineered articular cartilage from bovine articular chondrocytes, by supplementing cultures with transforming growth factor beta-3 (TGF-β3), seed cells in agarose scaffolds, and cultivating it in a novel centrifugal bioreactor (CBR) under oscillating hydrostatic pressure. The engineered tissue was characterized for chondrogenic markers as described above. The mechanical properties were quantified using AFM to estimate the elastic modulus. The presence of β-integrins and N-Cadherin on the surface of the chondrocytes was mapped by modifying the AFM cantilever tip with antibodies specific to these proteins to relay the structure to function relationship. We observed an improvement in chondrogenic markers when oscillating hydrostatic pressure is combined with TGF-β3 and when culturing within a scaffold. An enhancement in the elastic modulus is observed in comparison to static cultures; the elastic modulus approaches that observed in native articular cartilage in magnitude. In conclusion, the use of AFM provides insights that are missing from traditional quantitative and qualitative characterization techniques and can be used

62

to provide a more comprehensive picture of the structure-function relationship of engineered tissues in general and articular cartilage specifically. New Benchtop XES for Phosphorus and Sulfur Characterization

William M. Holden,1 Jennifer L. Stein,2 Brandi M. Cossairt,2 Singfoong Cheah,3 and Gerald T. Seidler1 Corresponding Author: holdenwm@uw.edu 1. Physics Department, University of Washington, Seattle, Washington, United States 2. Chemistry Department, University of Washington, Seattle, Washington, United States 3. National Renewable Energy Laboratory, Golden, Colorado, United States A new x-ray emission spectrometer has been developed for use in the 2-4 keV range, which enables new analytical capabilities for measurements of phosphorus and sulfur.1 X-ray emission spectroscopy (XES) is an advanced x-ray spectroscopic technique which allows element-specific, sensitive probing of the local electronic structure of atoms. When used for analytical purposes, it can have similar applications as XPS but provides bulk sensitivity and does not require vacuum conditions. However, despite the growing use of XES, access to the technique is typically limited to synchrotron facilities. For the special case of phosphorus and sulfur, only a handful of beamlines in the world are capable of performing measurements in the necessary 2-2.5keV energy range and only two are equipped with the needed endstation spectrometer. Here, we report the development of a laboratory spectrometer optimized in this energy range, along with recent studies demonstrating its utility for characterization of phosphorus and sulfur in environmental and analytical applications. The new instrument makes use of innovations in the optical layout and detector design to give fully synchrotron-level performance in the footprint of a laptop computer. Using these new capabilities, recent studies have been performed measuring oxidation state distribution of sulfur in biochar,3 as well as characterization of oxidized surface defects of phosphorus in InP quantum dots.4 In the case of biochar, despite having low sulfur concentrations (150-850 ppm S), the measured sulfur speciation by XES agreed well with prior synchrotron results.3 For phosphorus in InP quantum dots, the amount of surface oxidation was measured by XES for a range of different InP synthesis and shelling procedures and has been directly compared with solid-state 31P NMR, where the results agree but the XES requires far less measurement time and far less sample mass.4 References: [1] Holden, W. M. et al. A Compact Dispersive Refocusing Rowland Circle X-Ray Emission Spectrometer for Laboratory, Synchrotron, and XFEL Applications. Review of Scientific Instruments 2017, 88 (7), 073904. [2] Holden, W. M.; Hoidn, O. R.; Seidler, G. T. A Color X-Ray Camera for 2 – 6 KeV Using a Back-Illuminated Mass-Produced CMOS Sensor. J. Instrum. 2018, In preparation. [3] Holden, W.; Seidler, G. T.; Cheah, S. Sulfur Speciation in Biochars by Very High Resolution Benchtop Kα X-Ray Emission Spectroscopy. J. Phys. Chem. A 2018. [4] Stein, J. L.; Holden, W. M. et al. Probing Surface Defects of InP Quantum Dots Using Phosphorus Kα and Kβ X-Ray Emission Spectroscopy. J. Phys. Chem. C 2018, In preparation.

[5] This work was supported by the United States Department of Energy, National Science Foundation, Los Alamos National Laboratory, and the National Renewable Energy Laboratory. Synchrotron Near Ambient Pressure -XPS study of the inhibition of active sites in iron-nitrogen-carbon electrocatalyst for oxygen reduction reaction

Yechuan Chen, Plamen Atanassov and Kateryna Artyushkova Corresponding Author: kartyush@unm.edu Center for Micro-Engineered Materials, University of New Mexico, Albuquerque, NM 87106, Unites States of America. One of the most promising classes of PGM-free materials for oxygen reduction reaction (ORR) is based on graphene-like carbon containing nitrogen and transition metal (metal-nitrogen-carbon, MNC) [1], which show promise as replacement of Pt in both alkaline exchange membrane (AEM) and proton exchange membrane (PEM) fuel cells. It is well established that nitrogen coordination with metal in the carbon network of MNC materials is directly related to ORR activity [2]; however, the exact nature of the active sites is still debated. Understanding the specific roles of nitrogen and metal in the activity and durability of MNC-based catalytic materials is a prerequisite for the rational design of ORR electrocatalysts with improved performance.

The mechanism of ORR in MNC catalysts has been studied previously by a combination of spectroscopic and theoretical structure-to-activity studies [3-5]. Using inhibitors that have unique spectral signatures and have strong binding to the active sites allows elucidating the relationship between the chemistry of active sites and activity. We report results of synchrotron near ambient pressure X-ray photoelectron spectroscopic (NAP-XPS) analysis performed at ALS 9.3.2 beamline for series of electrocatalysts belonging to iron-nitrogen-carbon (FeNC) family. In-situ monitoring of oxygen binding to different nitrogen and metal moieties existing at the surface of these materials is performed with and without complexing inhibiting agent based on phosphonate (etidronic acid). The spectroscopic surface chemistry of inhibited active sites is correlated to an electrocatalytic performance from rotating ring disk electrode (RRDE) tests.

References: [1] J. Stacy, Y.N. Regmi, B. Leonard and M. Fan, The recent progress and future of oxygen reduction reaction catalysis: A review, Renewable and Sustainable Energy Reviews 69 (2017), 401-414. [2] K. Artyushkova, A. Serov, S. Rojas-Carbonell, and P. Atanassov, Chemistry of Multitudinous Active Sites for Oxygen Reduction Reaction in Transition Metal–Nitrogen–Carbon Electrocatalysts, The Journal of Physical Chemistry C 119 (2015), 25917-25928. [3] D. Malko, A. Kucernak, and T. Lopes, Performance of Fe–N/C Oxygen Reduction Electrocatalysts toward NO2–, NO, and NH2OH Electroreduction: From Fundamental Insights into the Active Center to a New Method for Environmental Nitrite Destruction, Journal of the American Chemical Society, 138 (2016), 16056-16068. [4] K. Mamtani, D. Jain, D. Zemlyanov, G. Celik, J. Luthman, G. Renkes, A.C. Co, and U.S. Ozkan, Probing the Oxygen Reduction Reaction Active Sites over Nitrogen-Doped Carbon Nanostructures (CNx) in Acidic Media Using Phosphate Anion, ACS Catalysis, 6 (2016), 7249-7259.

64

[5] J.L. Kneebone, S.L. Daifuku, J.A. Kehl, G. Wu, H.T. Chung, M.Y. Hu, E.E. Alp, K.L. More, P. Zelenay, E.F. Holby, M.L. Neidig, A Combined Probe-Molecule, Mössbauer, Nuclear Resonance Vibrational Spectroscopy, and Density Functional Theory Approach for Evaluation of Potential Iron Active Sites in an Oxygen Reduction Reaction Catalyst, The Journal of Physical Chemistry C, 121 (2017), 16283-16290. Theoretical study of the decarboxylation and decarbonylation of acetic acid over Pd (111)

Kingsley Chukwu1, Sean Seekins2, and Liney Árnadóttir1 Corresponding Author: Liney.Arnadottir@oregonstate.edu 1. School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR, 97331, United States 2. School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR, 97331, United States

3. School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR, 97331, United States The study of acetic acid (CH3COOH) decomposition over Pd (111) surface is a good model system to study decomposition of acids and oxygenates, which are common in biomass conversion. Understanding the reaction mechanism of acetic acid decomposition, at an atomic scale, will help us design more effective catalysts and catalyst systems. Here we present Density Functional Theory (DFT) calculations of the elementary steps involved in the decomposition of acetic acid on Pd (111). We investigated the reaction mechanism for both decarboxylation(DCX) and decarbonylation(DCN) of acetic acid and identified two major pathways for DCX and DCN. Both the DCX and DCN can proceed through dehydrogenation of acetic acid(CH3COOH) to acetate(CH3COO) or through α-carbon dehydrogenation of CH3COOH to Methylidene-1-ol-1-olate(CH2COOH). From the acetate the competition between DCN and DCX pathway depends on two endothermic routes, the deoxygenation of CH2COO to ketene(CH2CO) (Ea=0.98eV) and dehydrogenation of the carboxylmethylidene (CH2COO) to carboxylmethylidyne (CHCOO) (Ea=0.94eV). But our DFT results suggest that CH2CO is a stable intermediate in the decomposition of acetic acid over Pd (111). In the second major pathway through methylidene-1-ol-1-olate, the competition between DCN and DCX pathway depends on the dehydroxylation of carboxylic (COOH) to carbon monoxide (CO) (Ea=0.66eV) and dehydrogenation of COOH to carbon dioxide (CO2) (Ea=0.74eV). These calculations give an insight into the complexity of decompositions of oxygenations and the interplay between the different reaction routes.

High Resolution Multimodal Compositional Characterization of Nanocrystalline Soft Magnetic Materials

Trevor Clark1,2, Nicole Overman3, Xiujuan Jiang3, Suveen Mathaudhu2, and Arun Devaraj1 Corresponding Author: arun.devaraj@pnnl.gov 1. Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA 2. Mechanical Engineering, University of California, Riverside, Riverside, CA 92501, USA 3. Energy and Environmental Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA The unique coercivity behavior observed in amorphous and nanocrystalline soft magnetic materials can be understood through the random anisotropy model [1] to be dependent on grain size. However, the model fails to address other structure sensitive properties such as permeability, and domain wall motion which can be affected by local anisotropy variations due to compositional variation or defects. Because of the convolution of magnetic and structural information in transmission electron microscopy, understanding of how magnetic domains interact within complex nanostructured bulk samples with many types of defect interactions has proven difficult to probe. Here, an amorphous/nanocrystalline Fe based alloy with a rich variety of defects has been synthesized. Mossbauer studies [2] indicate that solute content influences the number of Fe nearest neighbor and next nearest neighbor interactions which effect local magnetic field and crystal structure. High resolution chemical mapping and correlated structural information is needed to gain insight on fundamental mechanisms of domain-defect interactions. Aberration-corrected scanning transmission electron microscopy, Lorentz transmission electron microscopy and atom probe tomography analysis methods are used to correlate magnetic domain behavior with specific nanoscale defects and features. The broader implication of this work is to make possible the exploration of fundamental physical interactions between nanoscale defects (such as grain boundaries, solute segregation, dislocations and voids) and the saturation magnetization, permeability and coercivity in novel bulk FeSi nanostructured soft- magnets. This knowledge could be harnessed to enable unprecedented improvements in magnetic properties and performance. References: [1] Giselher Herzer, “Modern soft magnets: Amorphous and nanocrystalline materials”, Acta Materialia, 61 (2013) 718-734. [2] Nicole R. Overman, Xiujuan Jiang, Ravi K. Kukkadapu, Trevor Clark, Timothy J. Roosendaal, Gregory Coffey, Jeffrey E. Shield, Suveen N. Mathaudhu, “Physical and electrical properties of melt-spun Fe-Si (3-8 wt.%) soft magnetic ribbons”, Materials Characterization 136 (2018) 212-220.

66

Comparative Analysis of Surface Configurations of CO Adsorbed on hcp and fcc Cobalt for the Fischer-Tropsch Synthesis

Greg Collinge1, Norbert Kruse1, Catherine Stampfl2, and Jean-Sabin McEwen1,3,4 Corresponding Author: js.mcewen@wsu.edu 1. Washington State University, The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Pullman, WA, USA. 2. The University of Sydney, Department of Physics, Sydney, Australia. 3. Washington State University, Department of Chemistry, Pullman, WA, USA. 4. Washington State University, Department of Physics and Astronomy, Pullman, WA, USA. The first step in Fischer-Tropsch (FT) synthesis over Co catalysts is carbon monoxide (CO) adsorption, which by and large out-competes dissociative hydrogen adsorption. Along with the fact that CO dissociation is not easy on the basal planes of Co catalysts, this fact implies that associatively adsorbed CO will likely have time to equilibrate with the imposed CO atmosphere and take on configurations relevant to the subsequent steps of the reaction. We present here a density functional theory (DFT) based investigation of these relevant configurations, taking into account the lateral interactions of CO through the construction of highly-predictive lattice gas models. Since both the face centered cubic (fcc) and hexagonal close packed (hcp) phases of Co have been shown to exhibit different FT activity, we compare these LG models and configurations as a function of the fcc and hcp phases; the primary difference being a large change in site-to-site distance (i.e. effectively different lattice strains). By utilizing the Alloy Theoretic Automated Toolkit [1] to generate a large variety of extended Co(111) and Co(0001) surfaces with different coverages and configurations of CO, we construct a large library of CO/Co(111) and CO/Co(0001) structures. A LG model is fit to these data and subsequently optimized to produce the most predictive model possible for each system. The results reveal a non-trivial change in the first nearest neighbor (NN) interaction energy, reflected in a much more favorable full-coverage in the hcp surface (see Figure 1). However, we are able to show that the ground states of these two systems are largely unchanged despite this difference. Our results facilitate experimentally relevant comparisons of the two systems and indicate what kind of surface structures one should expect to be present in the early stages of FT synthesis given an hcp vs. fcc Co-based catalyst. References: [1] A. van de Walle, M. Asta, and G. Ceder, The Alloy Theoretic Automated Toolkit: A User Guide, Calphad 26 (2002) 539-553.

[2] This work was supported by the National Science Foundation under contract No. CBET-1438227 and by the National Science Foundation Graduate Research Fellowship Program under Grant No. 1347973.

Figure 1. Surface energies (defined as θ×Eads) and associated LG predicted energies for the fcc Co (left) and hcp Co (right) systems.

Influence of Ambient Conditions on Inorganic EUV Photoresist Radiation Induced Chemistries Studied Using Ambient Pressure X-ray Photoelectron Spectroscopy

J.T. Diulus1, R.T. Frederick1, D.C. Hutchison2, I. Lyubinetsky1, M. Nyman2, and G.S. Herman1,2 Corresponding Author: greg.herman@oregonstate.edu 1. School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, OR, 97331, USA 2. Department of Chemistry, Oregon State University, Corvallis, OR, 97331, USA The semiconductor industry is rapidly transitioning from deep ultraviolet (DUV, λ = 193 nm) to extreme ultraviolet (EUV, λ = 13.5 nm) nanolithography, as the shorter wavelength photons allow higher resolution patterning.1 EUV photons lead to a significant change in patterning mechanisms, due to the creation of energetic electrons during exposure and associated modifications in resist chemistries.1 For example, tin-based materials have been suggested as promising EUV resists since tin atoms have ~30x higher photoabsorption cross section for EUV photons compared to carbon.1 Furthermore, organotin compounds are of interest since the tin-carbon bond is radiation sensitive. We are studying a charge-neutral butyltin β-Keggin [NaO4(BuSn)12(OH)3(O)9(OCH3)12(Sn(H2O)2)] nanocluster to evaluate radiation chemistries for high contrast patterning.2 By using a model, charge-neutral cluster, we can gain fundamental mechanistic insights during radiation exposure without complications from charge-balancing counterions. Prior studies have shown that irradiation of butyltin β-Keggin in low oxygen pressures increased the rate of butyl group decomposition.2 To further understand the role of oxygen pressure on photoresist sensitivity we have used ambient pressure X-ray photoelectron spectroscopy (APXPS). For these experiments, we have measured the change in the required photon dose for the solubility transition in UHV and multiple oxygen and D2O pressures. APXPS spectra were evaluated to determine the chemical changes that occur due to both radiation and thermal exposure in the presence of each gas. In Figure 1 we show contrast curves that indicated increasing the oxygen pressure lowers the photon dose necessary for the solubility transition, while increasing the D2O pressure increases the required photon dose.2 Furthermore, post-exposure bakes in different ambients had very little effect on the chemistry of the films. These studies ultimately provide a better understanding of the patterning processes that could aid in the design of improved EUV photoresists and processing conditions for nanolithography.

Figure 1. Contrast curves were determined for three separate ambient conditions: UHV (black, square), 𝑃𝑃𝑂𝑂2 = 1 mbar (red, triangle), and 𝑃𝑃𝐷𝐷2𝑂𝑂 = 1 mbar (blue, circle).

References: [1] Li, L.; Liu, X.; Pal, S.; Wang, S.; Ober, C. K.; Giannelis, E. P. “Extreme ultraviolet resist materials for sub-7 nm patterning” Chem. Soc. Rev. 46, (2017), 4855-4866. [2] J.T. Diulus, R.T. Frederick, D.C. Hutchison, I. Lyubinetsky, M. Nyman, and G.S. Herman, “Surface characterization of tin-based inorganic EUV resists,” (in preparation).

68

The study of the energetics and geometries of dodecaborate complexes and polysulfide clusters with photoelectron spectroscopy and theoretical calculations

Zhipeng Li1, 2, Qinqin Yuan1, and Xuebin Wang*, 1 Corresponding Author: Xuebin.Wang@pnnl.gov 1. Pacific Northwest National Laboratory, Physical Sciences Division, Richland, USA 2. East China Normal University, State Key Laboratory of Precision Spectroscopy, Shanghai, China Dodecaborate and polysulfide clusters have been discussed for decades, owing to their tremendous academic and application potentials, such as being used as electrolytes in lithium batteries and being effective materials in boron neutron capture therapy (BNCT). Biological tests have revealed that the complexes with the hydrophobic cyclodextrin (CD) cavities can help B12F12

2- to overcome its hydrophilicity to penetrate through the lipophilic cell membranes. Sodium-sulfur (NAS) and lithium-sulfur (Li-S) are two important achievements among those high-performance batteries developed to meet the increasing energy storage requirement in past few years, and both involve polysulfide clusters.

To give a better understanding of the energetics and geometries of dodecaborate complexes and polysulfide clusters, we performed combined experimental and theoretical investigations on these two systems recently. Cryogenic Photoelectron spectra of B12X12

2-·(C6H10O5)n (X = H, F and n = 6-8) and NaSn

− (n = 5-9) are obtained. Quantum chemical calculations are employed to identify the optimized structures of these two series of cluster complexes, and to compute their detachment energies in direct comparison with the experiments.

Molecular Examination of Ion Solvation using in situ Liquid SIMS

Wen Liu1*, Yanyan Zhang2, Zihua Zhu3 Corresponding Author: wliu711@gmail.com 1. State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, P. R. China; 2. Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China; 3. W. R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354 USA.

Ion-solvent interactions are of great fundamental and practical importance in chemical, environmental, biological, and health-related processes, which have received widespread attention. Computational approaches have been a popular way to the investigations of ion-solvent interactions. However, computational investigation of ion solvation generally starts from quantum calculation of simple structures, and the results have been hard to be verified by experimental methods. Traditional experimental techniques, such as IR, NMR, and Raman, have been devoted to this topic, but they share a common limitation of providing only “chemical shift” information in bulk liquids, and such results could not be used to test the structure and stability of small molecular clusters in computational work. In situ liquid secondary ion mass spectrometry (SIMS) recently developed in our group allows us to directly analyze liquid to obtain molecular information. In this poster, we used non-aqueous electrolytes in lithium ion batteries as an example and applied liquid SIMS to examine formation of solvated ions and ion clusters. Results provided

solid molecular evidence for preferential solvation, coordination number of Li+ ions, as well as formation of ion clusters. Our SIMS data suggest the preferential solvation is stronger than the prediction in previous computational work. Moreover, we have also examined solvation of H+ in aqueous environment, and the data are consistent with previous computational results. The above results suggest in situ liquid SIMS is a powerful and sensitive experimental tool to elucidate the ion-solvent interactions.

Low temperature nanopatterning on Graphite via carbon gasification reaction using cobalt oxides

C. Morales1, D. Díaz-Fernández2, Pilar Prieto1, Carlos Escudero3, Virginia Pérez-Dieste3, J. Méndez4 and L. Soriano1 Corresponding Author: carlos.morales@uam.es 1. Applied Physics Department and Instituto de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, Cantoblanco E-28049 Madrid, Spain. 2. Advanced Materials Department, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia. 3. ALBA Synchrotron Light Source, Carrer de la Llum 2-26, E-08290 Cerdanyola del Vallès, Barcelona, Spain 4. Material Science Center of Madrid, ICMM-CSIC, Cantoblanco E-28049 Madrid, Spain Cobalt properties at macroscopic scale have been thoroughly characterized in the last decades for a wide variety of industrial processes. However, its interaction and effects on carbon-based systems at the nanoscale has recently attracted much attention as catalyzer of carbon nanotubes (CNTs) [1] or at graphene and graphite nanochanelling taking advantage of its ferromagnetic behavior [2]. Experiments performed at our laboratories show how the re-oxidation process at 400 °C in oxygen atmosphere of 2 equivalent monolayers of CoO deposited on HOPG leads to the formation of nanochannels at lower temperature than using other methods [3]. Here we present the in-situ characterization of the kinetics of the carbon gasification reaction which rules this process by means of near ambient pressure XPS (NAP-XPS) performed at the synchrotron facility ALBA. The reason why this reaction occurs at much lower temperatures compared to other methods is interpreted as due to the weakening of the carbon σ bonds by the initial wetting CoO layer [4] formed at the early stages of growth of CoO on the HOPG surface. Besides nanochannels, ex-situ AFM measurements also show the appearance of two more kind of nanostructures: nanostrips and nanorings. These could be related with carbon based structures as initial stages of CNTs or with unidimensional Co-O chains. Although its nature and properties are still unclear, it reveals the impressive catalytic power of Co on carbon based systems.

70

Figure 1 (a) NAP-XPS C 1s spectra at RT and O2 (1 mbar) before re-oxidation process. (b) Ex-situ AFM topography image after re-oxidation process with all the final nanostructures. (c) AFM detail. References: [1] D. S. Bethune, et al.; Nature (1993); 363. 605-607 [2] Bulut L, Hurt RH. Adv Mater (2010); 22:337. [3] Díaz-Fernández D, et al.; Carbon (2015); 85:89. [4] D. Díaz-Fernández, et al. Surface Science, (2014) 624. 145-153 Accounting for beam driven damage events of soft materials within liquid cell transmission electron microscopy experiments Trevor H. Moser1,2, Hardeep Mehta1, Chiwoo Park3, Ryan T. Kelly1, Tolou Shokuhfar2,4,* and James E. Evans1,*

Corresponding Authors: James.Evans@pnnl.gov and Tolou@UIC.Edu 1 Environmental Molecular Sciences Laboratory, 3335 Innovation Blvd., Richland, WA USA 99354 2 Michigan Technological University, 1400 Townsend Dr., Houghton, MI USA 49931 3 Florida State University, 600 W. College Ave., Tallahassee, FL USA 32306 4 University of Illinois Chicago, 1200 W. Harrison St., Chicago, IL 60607 Electron irradiation of materials can result in damage in the form of primary damage, where atoms are displaced from their lattice or atomic bonds are broken, and secondary damage, where radicals produced by bond breakage or secondary electrons emitted can cause further damage1. Secondary damage from radical production is especially important for liquid cell transmission electron microscopy (LC-TEM) where these radical species are mobile within the liquid environment and can substantially affect the chemistry of the system2. Understanding how the chemistry of the liquid sample is impacted by irradiation is a critical component of accurate interpretation of LC-TEM observations3. Using custom LC-TEM devices we demonstrate the effect of irradiation history on the growth and nucleation rates of silver nanoparticles which have been precipitated by the electron beam, as well as the sensitivity of biological samples to fluxes well below thresholds which have been determined for cryogenic electron microscopy.

Figure 1: Effect of cumulative electron irradiation on the soil bacterium C. metallidurans demonstrating the sensitivity of biological samples at substantially lower electron fluxes than those established for cryogenic electron microscopy. 1 Baker, L. A. & Rubinstein, J. L. Radiation Damage in Electron Cryomicroscopy. Method

Enzymol 481, 371-388, doi:10.1016/S0076-6879(10)81015-8 (2010). 2 Schneider, N. M. et al. Electron–Water Interactions and Implications for Liquid Cell

Electron Microscopy. The Journal of Physical Chemistry C 118, 22373-22382, doi:10.1021/jp507400n (2014).

3 Woehl, T. J. & Abellan, P. Defining the radiation chemistry during liquid cell electron microscopy to enable visualization of nanomaterial growth and degradation dynamics. J Microsc 265, 135-147, doi:10.1111/jmi.12508 (2017).

Surface X-ray Diffraction Study of Interfacial Conduction in Complex Metal Oxides

Widitha Samarakoon1, Jin Yue2, Peng Xu2, Peter V. Sushko3, Scott A. Chamber3, Jalan Bharat2, Zhenxing Feng1 Corresponding Author: zhenxing.feng@oregonstate.edu 1. School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, Oregon, 97331, United States. 2. Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, 55455, United States. 3. Physical & Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington, 99352, United States. Understanding the mechanisms of electronic phenomena at polar-nonpolar interfaces is an integral part in interpreting the properties of complex metal oxides, such as the two-dimensional electron gas (2DEG) in NdTiO3/SrTiO3 (NTO/STO) interfaces. Our previous work has demonstrated that STO/ 1 u.c. NTO/STO (001) exhibits metallic conductivity with a carrier density equal to 0.5 e-

/u.c, and the carrier density in such sandwich structures can be tuned by the Nd vacancies. Here we design two different structures, namely, 8 u.c. STO/x u.c. NTO/8 u.c. STO/LSAT (001) with x=1 and 2, grown by hybrid molecular beam epitaxy (MBE). To understand the role of Nd vacancies in controlling the carrier density, we performed surface X-ray diffraction in combination of coherent Bragg rod analysis (COBRA) to obtain the 3-dimensional atomic structure with layer-by-layer composition information. These results provide comparison platform to study the physical origin of interfacial conductivity in model oxide systems.

72

An Investigation of Solvent Effects in the Decomposition of Acetic Acid using Density Functional Theory and Ambient Pressure X-Ray Photoelectron Spectroscopy

Sean Seekins, Kingsley Chukwu, and Líney Árnadóttir Corresponding Author: liney.arnadottir@oregonstate.edu School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis Oregon, United States Heterogeneous catalytic reactions are an essential part of chemical processes such as the production of fuels, commercial products, and pharmaceuticals. Many of these reactions occur in ambient conditions, high pressures, or in the presence of a liquid solvent. Most of our atomistic understanding of these reactions comes from surface science and ultrahigh vacuum research studies. In this work we start bridging the gap between ultrahigh vacuum and industrial conditions by combining near ambient pressure x-ray photoelectron spectroscopy (NAP-XPS) and density functional theory (DFT) to investigate the effect of various solvents on the decomposition of acetic acid and ethanol on the Pd (111) surface. DFT is used to calculate binding energies, reaction energies, and transition states, both in vacuum conditions and in the presence of solvents. The solvent calculations are performed either through an implicit solvent calculation (VASPsol), or by explicitly adding individual water molecules or a water bilayer to each elementary step in the reaction pathway. NAP-XPS studies of acetic acid on Pd (111) at different water partial pressures are used to confirm the theoretical results. Previous work has shown that reaction pathways can be altered in the presence of a liquid solvent through changes in reaction and activation energies [1]. Implicit solvent calculations can accurately model solvent effects in reaction steps that do not include hydrogen bonding, or have equal amounts of hydrogen bonding in the product and reaction states [2]. Combining explicit and implicit methods can reduce the computational time required to model a reaction pathway without sacrificing accuracy if hydrogen bonding is modeled correctly. We aim to advance the understanding of solvent effects in heterogeneous catalysis by analyzing reaction steps in acetic acid decomposition through the use of DFT calculations supported by NAP-XPS experiments. These studies will help us better understand the role of different solvents in catalytic processes. References: [1] D. Hibbitts, B. Loveless, M. Neurock and I. Iglesia, Mechanistic Role of Water on the Rate and Selectivity of Fischer-Tropsch Synthesis on Ruthenium Catalysts, Heterogeneous Catalysis 50.27 (2013), 12273-12278. [2] S. Kumar, A. Deskins, Evaluating Solvent Effects at the Aqueous/Pt (111) Interface, ChemPhysChem, 18.16 (2017), 2171-2190. [3] Acknowledgements to the National Science Foundation under Grant No. 166528 for support of this research. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

The role of the -OH groups of (hydroxyethyl)methacrylate (HEMA) on KGF conformational dynamics at the surface of HEMA-based hydrogels Shohini Sen-Britain, Joseph A. Gardella Jr. Corresponding Author: ssen3@buffalo.edu Department of Chemistry, State University of New York at Buffalo, Buffalo, NY, USA HEMA based hydrogels can deliver proteins and growth factors, such as Keratinocyte growth factor (KGF), in a precise and controlled manner. KGF stimulates epithelial cell migration and proliferation, and exogenous application of KGF enhances wound healing. HEMA-mediated delivery could enhance the therapeutic effects caused by KGF. In this study, we investigated the hydrogel/protein interface throughout the uptake and release process, for the purpose of delivering conformationally active protein to the wound site. From FTIR-ATR spectra of KGF at the hydrogel surface, we hypothesized that -OH groups of HEMA interact with the receptor binding loop and the disordered beta sheet of KGF to mimic KGF-receptor interactions, resulting in eventual denaturation of KGF. We tested this hypothesis by identifying how removal of -OH groups from the surface influenced KGF conformation. We modulated the surface availability of –OH groups through addition of methyl methacrylate (MMA), a hydrophobic monomer, to the HEMA hydrogels. I will discuss (1) effects of addition of MMA on (a) surface crosslinking of the polymer chains and (b) surface vs. bulk content of MMA and HEMA-specific secondary ions, and (2) testing of our mechanistic hypothesis by ToF-SIMS and FTIR-ATR spectroscopy of KGF on these MMA/HEMA blends. We identified the effects of -OH group surface availability on KGF conformational changes through PCA of KGF amino acid elative intensities from the SIMS data.

Figure 1 (a) KGF interactions with hydrogels (b) FTIR-ATR spectra of KGF at hydrogel surface (c) mechanistic hypothesis of KGF-HEMA interaction References:

(1) Hicks et al., Arch Otolaryn Head Neck Surg, Vol. 130, Apr 2004, 446-449 (2) Castner et al. Langmuir, 2002, 18, 4090-4097

(a) (b) (c)

74

A macro-scale and solution-based approach towards a mixed semi-conducting and organically functionalized surface

Yi Zhang and David Y. Lee Materials Science and Engineering Program Washington State University Thiolate and porphyrin monolayers have been widely used to chemically functionalize surface materials and provide researchers with a broad range of customizability via molecular modification before surface deposition. We present a new solution-based procedure to functionalize a common metal surface with both thiolate and porphyrin species. This method involves only mild-temperature incubation and can be easily adopted by research labs that do not have vacuum-based deposition technology. The mixed monolayer has at least centi-meter scale coverage and have been imaged in an ambient condition with nano-meter scale resolution.

The Effect of Irradiation on TiO2 for Lithium Ion Batteries

Kassiopeia Smith1, Janelle Wharry2, Darryl Butt3, and Hui Xiong1 Corresponding Author: kassiopeiasmith@u.boisestate.edu 1. Micron School of Materials Science & Engineering, Boise State University, 1910 University Drive, Boise ID 83725 2. School of Nuclear Engineering, Purdue University, 400 Central Drive, West Lafayette IN 47907 3. College of Mines and Earth Sciences, University of Utah, 115 S 1460 E, Salt Lake City, UT 84112 We are living in a time of growing concerns over population growth, energy consumption, and climate change. These issues are driving the need for advanced electrochemical energy storage (EES) technologies, such as batteries, to support a shift to renewable energy sources. Among current battery technologies, LIBs offer the highest energy density. After their commercialization in the 1990’s LIBs have dominated the field of portable electronics, and have become one of the most promising EES systems for renewable energy systems. Even so, future demands will require LIBs to offer increased energy and power density, improved safety, and longer cycle life. As such, recent studies have investigated enhanced electrochemical charge storage in electrodes that contain intentional structural defects. With this in mind, we aim to understand the fundamental effects of irradiation on nanostructured metallic oxides, and how these effects may alter the electrochemical response. Unfortunately, nanostructuring a material dramatically complicates the characterization of irradiation response, and so in addition to looking at our structure of interest, TiO2 nanotubes, we must also take a step back and look at how irradiation plays a role in the microstructure of TiO2 without the complications of grain boundaries and high surface areas. The long-term goal of this research is to utilize irradiation to enhance energy density and safety of rechargeable Li-ion batteries (LIBs), and to provide power for applications under extreme conditions.

Synthesis of Mg-MOF-74 thin film and potential CO2 sensing application

Hao Sun, Yujing Zhang and Chih-hung Chang* * Corresponding Author: chih-hung.chang@oregonstate.edu 1. Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, United States. Mg-MOF-74, a metal-organic framework (MOF) that is widely known by its excellent CO2 uptake ability, shows the interest in helping detect low levels of toxic gases such as CO2. Currently, most research into Mg-MOF-74 focuses on using powder as a CO2 absorbent because it requires mere relatively simple batch reaction. However, in order to lower the cost and expand the potential application of Mg-MOF-74, it would always be promising to develop direct thin film synthesis. Currently there is limited research on Mg-MOF-74 thin film synthesis, of which solvothermal method is usually chosen though it is fairly complicated and results in a long reaction time. This study aimed at achieving the growth of high quality Mg-MOF-74 thin film in an easy-controlling and cost-effective way. The result showed that a dense and continuous Mg-MOF-74 thin film was successfully synthesized on glass slide with a thickness of ~800 nm after only 5 drop-casting layers. The thin film thickness could be easily manipulated by adjusting the drop-casting layers. Moreover, by the synthesis of thin film on optical glass slide it brightens the future of Mg-MOF-74 for optical CO2 gas sensing. X-ray diffraction, scanning electron microscope, UV-VIS spectroscopy, Fourier-transform infrared spectroscopy and Brunauer–Emmett–Teller analysis were conducted in characterization. This work builds up a foundation for economical large-scale production of Mg-MOF-74 thin films in the future. In Situ Studies of Electrocatalyst for Oxygen Evolution Reaction in Acidic Condition Using a Combination of X-ray Scattering and Spectroscopy

Maoyu Wang, Widitha Samarakoon, Zhenxing Feng,* Corresponding Author: zhenxing.feng@oregonstate.edu School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, Oregon, 97331, United States Exploitation of fossil energy has increased the atmospheric CO2 concentration, which leads to severe climatic problems. Clean fuels such hydrogen and oxygen produced from water splitting provide alternative solutions for green energy conversion and production. However, since the efficiency of the water splitting reaction is largely limited by the high overpotential required by the oxygen evolution reaction (OER) and the relatively slow kinetics of the OER, high-performance and stable electrocatalysts are required. As the electrocatalytic reactions strongly depend on the surface atomic structures of the electrocatalysts, in this work, we have combined in situ X-ray diffraction and X-ray absorption spectroscopy to study nanocatalysts that consist of a Pd core in a IrO2 shell with two different surface morphologies, namely one with a flat surface and the other with a concave surface. We found that the concave sample undergoes atomic structural and oxidation state changes during the process while the flat one showed no change. In addition, cyclicvoltammetry tests conducted on both concave and flat samples reveal that concave sample shows a relatively lower overpotential compared to the flat sample. Our in situ measurements can be correlated with their stability and activity and the insights learned from this study can provide ways to design and control cost-effective and efficiency catalysts for OER.

76

Localized Surface Plasmon Resonance Enhanced Carbon Dioxide Gas Sensing based on Nanostructured Covellite Copper Sulfide Thin Film

Yujing Zhang1, Xinyuan Chong2, Hao Sun1, Muaz M. Kedir1, Ki-Joong Kim1, Paul R. Ohodnicki3, Alan Wang2 and Chih-hung Chang*1 Corresponding Author: chih-hung.chang@oregonstate.edu 1. School of Chemical, Biological Environmental Engineering, Oregon State University, Corvallis, OR 97331, USA. 2. School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331, USA. 3. National Energy Technology Lab, United States Department of Energy, Pittsburgh, PA 15236, USA. Infrared (IR) technique is commonly used for carbon dioxide (CO2) gas sensing due to its high sensitivity, selectivity and stability. However, the IR apparatus is usually expensive and commonly difficult to achieve miniaturization. Therefore, there is a need to investigate new approach of low-cost IR sensing. Covellite copper sulfide (CuS), a non-toxic, low-cost and earth-abundant material that exhibits intense and broad localized surface plasmon resonance (LSPR) throughout the near-IR and extend to middle-IR region, shows the potential as LSPR-based sensing material. In this work, CuS thin films were facially synthesized on cheap optical glass by a modified successive ionic layer adsorption and reaction at room temperature and annealed at a low temperature in air, which introduces a sustainable production of such material. The annealed CuS thin films possessed a nanostructure consisting of CuS nanoflakes and exhibited suitable optical property for IR gas sensing. The resulting CuS-based thin film sensor demonstrated a low detection limit of 100 ppm for CO2 with a 224% IR absorption enhancement.

A Graphene-Based Ambipolar Vacuum Transistors Gongtao Wu, Xianlong Wei Department of Electronics Peking University Beijing 100871, P. R. China Corresponding Authors: wugt@pku.edu.cn, weixl@pku.edu.cn Vacuum transistors exhibit merits of being faster and more resistant to extreme environments such as high temperature and intense irradiation when compared to their solid-state counterparts. Here, by employing an electrically-biased graphene as the electron emitter, a vacuum transistor with a ON/OFF current ratio up to 106, a subthreshold slope of 120 mV/dec and a working voltages less than 10 V is experimentally demonstrated by using traditional microfabrication technologies.[1]

The use of microfabrication technologies makes it feasible to achieve more complex device functions by integrating the graphene-based vacuum transistor (GVT) in a way similar to the integration of MOS FETs. By integrating two GVTs, we achieve an ambipolar transistor with perfectly symmetric transfer characteristics centered at 0 V and a ON/OFF current ratio up to 103 (Figure 1). The ambipolar vacuum transistor shows the potential in AC applications such as frequency multipliers and rectifiers in extreme environments.

Figure 1. (a)Schematic structure and work principle of ambipolar device. (b) Scanning electron microscope image of an ambipolar device integrate on SiO2/Si substrate. (c) Transfer characteristics of GVTs when they work separately at VC=15 V. (d) Transfer characteristics of the ambipolar device in (a) when VC=15 V and electric potential of the ground electrode 1 and 2 is set to be 3.40 and -3.33 V, showing perfectly symmetric ambipolar characteristics. References [1] Wu G, Wei X, Gao S, et al. Tunable graphene micro-emitters with fast temporal response and controllable electron emission[J]. Nature communications, 2016, 7: 11513. [2] Wu G, Wei X, Zhang Z, et al. A Graphene-Based Vacuum Transistor with a High ON/OFF Current Ratio[J]. Advanced Functional Materials, 2015, 25(37): 5972-5978. Lab-based XAFS and XES for materials chemistry research

Evan Jahrman1, Gerald T. Seidler1, William Holden1, Alex Ditter1,2, Devon Mortensen1,3, Timothy T. Fister1,4, Stosh A. Kozimor2, Beth Mundy5, Brandi M. Cossairt5, and John R. Sieber6

Corresponding Author: ejahrman@uw.edu 1. University of Washington, Physics, Seattle, Washington, USA. 2. Los Alamos National Lab, Chemistry Division, Los Alamos, New Mexico, USA. 3. easyXAFS LLC, Seattle, Washington, USA. 4. Argonne National Lab, Chemical Sciences & Engineering Division, Lemont, Illinois, USA. 5. University of Washington, Chemistry, Seattle, Washington, USA. 6. NIST, Chemical Sciences Division, Gaithersburg, MD, USA Over the last four years, our group at the University of Washington developed several new families of lab-based instruments to expand the accessibility of advanced x-ray spectroscopies, including x-ray absorption fine structure (XAFS) and x-ray emission spectroscopy (XES).1-4 Here, we present the construction of a new, lab-based spectrometer with advances geared toward increased ease-of-use, design simplicity, and overall instrument throughput – all while maintaining synchrotron-quality energy resolution. The above features, along with a low signal-to-noise ratio, recommend the instrument to dilute systems, weak transition lines, and exploratory materials

78

campaigns. In addition to a survey of the instrument’s design, we establish current capabilities and highlight the tool’s relevance to materials research. From the standpoint of materials inquiry, we will present a wide range of results, including XAFS and valence-to-core XES measurements of NMC and VOPO4 cathode materials, a quantitative analysis of the hexavalent chromium fraction in dilute samples of environmental interest5, a preliminary study of ion pairing in electrolyte materials, and XANES characterizations of transition metal phosphide nanoparticles of high electrocatalytic activity. The present work advocates for laboratory-based instrumentation as a promising avenue for high-access and high throughput x-ray spectroscopy analysis for both basic and applied research programs. References: [1] W. M. Holden, et al., “A Compact Dispersive Refocusing Rowland Circle X-ray Emission Spectrometer for Laboratory, Synchrotron and XFEL Applications”, Rev. Sci. Instrum. 88, 073904 (2017). [2] G. T. Seidler, et al., “A Laboratory-based Hard X-ray Monochromator for High-Resolution X-ray Emission Spectroscopy and X-ray Absorption Near Edge Structure Measurements,” Rev. Sci. Instrum. 85, 113906 (2014). [3] G. T. Seidler, et al., “A Modern Laboratory XAFS Cookbook,” Journal of Physics: Conference Series 712, 012015 (2016). [4] D. R. Mortensen, et al., “Benchtop Nonresonant X-ray Emission Spectroscopy: Coming Soon to Laboratories and Beamlines Near You,” Journal of Physics: Conference Series 712, 012036 (2016). [5] E. P. Jahrman, et al., “Determination of Hexavalent Chromium Fractions in Plastics Using Laboratory-Based, High-Resolution X-ray Emission Spectroscopy,” J. Analyt. Chem. In Press (2018). [DOI: 10.1021/acs.analchem.8b00302]

Poster Session - Thursday, June 21 - Surface Analysis ’18

Poster Number

Title and Presenter Note

1 Bottom-up growth of micropatterned organic single-crystals Sebastian Ceaser, Western Washington University

Undergraduate

2 Magnesium corrosion studies using Cryo-XPS analysis Abraham Martinez, Pacific Northwest National Laboratory

Undergraduate

3 Submonolayer island nucleation and growth in solution-processed organic thin films Griffin Reed, Western Washington University

Undergraduate

4 Large, nearly constant absorption coefficient in NbxTi1-xO2 thin films throughout the visible range Adam E. Shimabukuro, University of Washington

Undergraduate

5 3D structural analysis of 3D printed parts to support new anti-counterfeiting measures Tanner Ricketts, Pacific Northwest National Laboratory

High School

6 ToF-SIMS analysis on the transformation of clay-sorbed nitrogen by acidogenic bacteria Burkholderia glathei Wen Liu, China University of Geosciences

7 Plant imaging using delayed extraction time-of-flight secondary ion mass spectrometry Rachel Komorek, Pacific Northwest National Laboratory

8 Reflection electron energy loss spectroscopy for determining optical constants of actinide surfaces Art J. Nelson, Lawrence Livermore National Laboratory

9 Dynamic SIMS for materials analysis in nuclear science Paula Peres, CA.M.ECA/Ametek/Nu France

10 Visualizing Li metal interaction with LiCoO2 thin film cathodes using in situ TEM Phuong-Vu Ong, Pacific Northwest National Laboratory

11 Uranium particles analysis and imaging using ToF-SIMS for source identification Juan (Jenn) Yao, Pacific Northwest National Laboratory

12 Engineering correlation effects of 5d transition metal oxide SrIrO3 via artificially designed superlattices Jishan Liu, Shanghai Institute of Microsystem and Technology Information

80

Surface Analysis ‘18 Poster Abstracts

Thursday, June 21 Bottom-Up Growth of Micropatterned Organic Single-Crystals

Sebastian Ceaser1, Matthew Littleton1, Griffin Reed1, Cyrus Schaaf1, Brad L. Johnson2, David L. Patrick1,* *Corresponding Author: david.patrick@wwu.edu 1. Western Washington University, Dept. of Chemistry, Bellingham, WA, USA. 2. Western Washington University, Dept. of Physics, Bellingham, WA, USA. The ability to process single-crystal inorganic semiconductor materials such as c-Si into complex 2D and 3D microarchitectures has enabled countless important technological innovations, from integrated circuits, to solid-state optical devices and micro-electro-mechanical systems. For single-crystal organic semiconductors on the other hand, comparable approaches to defining micron- and submicron-scale structure are comparatively nonexistent. Here we describe a new bottom-up crystal growth strategy enabling a comparable level of control in organic single-crystals, grown into intricate terminal shapes by design. Crystal shape is controlled using a 2-dimensional vapor-liquid-solid deposition technique on substrates patterned with micron-scale obstructions, causing crystals to adopt shapes and growth directions accommodating the obstructions. After growth is complete, patterned crystals can be released from the substrate. The successful development of methods for programming bottom-up growth of molecular single-crystals with geometries approaching the complexity of micropatterned inorganic solids could open the door to new generations of molecular devices with tailored electronic, optical, photonic and other properties.

Figure 1 (top left) A polarized optical micrograph of a single-crystal of the organic semiconductor tetracene grown from the bottom-up to intrinsically incorporate a regular array of penetrating 2 µm diameter circular holes. (top right) A similar tetracene single-crystal after lift-off and transfer to a ridged PDMS stamp. Hole diameter is 10 µm. (bottom) A tetracene single-crystal with an array of square holes.

Magnesium Corrosion Studies using Cryo-XPS Analysis Abraham Martinez1, Vaithiyalingam Shutthanandan1, Arun Devaraj2, Elizabeth Stephens3, Olga A Marina3, Vineet Joshi3, Suntharampillai Thevuthasan1 and Vijayakumar Murugesan2 1 Environmental Molecular Sciences Laboratory 2 Physical and Computer Science Directorate 3 Energy and Environmental Directorate Pacific Northwest National Laboratory Richland, WA, USA The demand for new, stronger and lighter materials is increasing throughout the automotive, aerospace and general transportation industry [1]. The prominent material of interest has been magnesium and its subsequent alloys. In recent years, these materials have been heavily researched because of their high strength to weight ratios and additive strength when alloyed with other lighter metals [1, 2]. Although promising, applications for these materials are limited because of magnesium’s sensitivity to oxidation and corrosion [2]. Ability to designing new materials will critically depend on the fundamental understanding of the chemical and corrosive processes. Researchers in the past have characterized the corrosion behaviors of these materials utilizing ex-situ capabilities such as x-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) where materials were exposed to corrosive/wet environments for prolonged periods of time [2]. In this work, we have attempted to analyze the corroded surfaces of magnesium using in-situ XPS in a cryogenic environment. Two sputter cleaned single crystal samples of magnesium (0001) were exposed to droplets of pure D2O and 5 wt% NaCl in D2O solutions, in a controlled glove box environment for 60 minutes. After the reaction, both samples were cooled down to -120°C using a liquid nitrogen heat exchanger and transported to the XPS analysis chamber in their frozen states. The chemical speciation on the exposed surfaces were monitored as a function of temperature from -120°C to room temperature. Furthermore, high resolution helium ion microscopy imaging was employed to capture the reacted NaCl exposed surface, revealing the micro development of surface morphologies and cubic crystals. Discussion on the results and their implications will be discussed in this presentation. References [1] Philippe Dauphin-Ducharme, Janine Mauzeroll. Surface Analytical Methods Applied to

Magnesium Corrosion, ACS Publications 87 (2015), 7499-7501. [2] M. Esmaily, J.E. Svensson, S. Fajardo, et al., Fundamentals and Advances in Magnesium

Alloy Corrosion, Progress in Materials Science 89 (2017), 92-120.

82

Submonolayer Island Nucleation and Growth in Solution-Processed Organic Thin Films

Griffin Reed1, Linnea Bavik2, Matthew Littleton1, Sebastian Ceaser1, Brad L. Johnson2, David L. Patrick1,* *Corresponding Author: david.patrick@wwu.edu 1. Western Washington University, Dept. of Chemistry, Bellingham, WA, USA. 2. Western Washington University, Dept. of Physics, Bellingham, WA, USA. Over the past several decades, studies of submonolayer island nucleation and growth kinetics by vacuum deposition have produced a sophisticated understanding of the connections between structural film properties such as the island size and inter-island spacing distributions, and the underlying atomistic processes of monomer deposition, diffusion and aggregation. By comparison, the theoretical understanding of polycrystalline films formed in a liquid solvent is much less developed. In this poster, we introduce a comprehensive treatment of solution-based film formation enabling quantitative prediction of domain formation rates, coverage, and spacing statistics based on a small number of experimentally-measureable parameters. The model combines a mean-field rate equation treatment of monomer aggregation kinetics with classical nucleation theory and a supersaturation-dependent critical nucleus size to solve for the quasi-two-dimensional temporally- and spatially-varying monomer concentration, nucleation rate, and other properties. Excellent agreement is observed with measured properties of polycrystalline tetracene films. Film formation is observed in real-time using fluorescence videomicroscopy, enabling direct observation of the micron-scale spatiotemporal evolution of monomer concentration field, island sizes, and positions.

Figure 1 Polarized optical micrograph of a submonolayer tetracene films grown in a thin layer of the solvent squalane. We describe a new model predicting the number of crystals nucleated per unit area, their spacing statistics, and the time-dependent evolution of the monomer concentration field, and compare the results to experiment. References: [1] Schaaf et al, Phys. Rev. Mater. 2017, 1, 043404 [2] This work was primarily supported by the National Science Foundation under Grant Number DMR-1508591.

Large, Nearly Constant Absorption Coefficient in NbxTi1-xO2 Thin Films throughout the Visible Range

Adam E. Shimabukuro1, Akihiro Ishii2, Fumio S. Ohuchi1 and Hitoshi Takamura2

Corresponding Author: Adam Shimabukuro shimaa2@uw.edu 1. Department of Materials Science and Engineering, College of Engineering, University of Washington, Seattle 98195, USA 2. Department of Materials Science, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan

Figure 1 (a) Absorption spectra of deposited films from the UV to near IR range (b) The visible range absorption spectra of deposited films compared to literature data of Fe3O4

[1], Titanium nitride[2] and Si[3] (c) The appearances of selected deposited films. In this study, we report on the optical absorption properties of the reduced oxides NbO2, Ti4O7 and NbxTi1-xO2 thin films prepared in high vacuum by pulsed laser deposition (PLD) at 600 ˚C. Whereas Nb2O5 and TiO2 are typically transparent, their oxygen deficient analogs, NbO2 and Ti4O7 have remarkably different electronic structures and show coloration[4–6]. We synthesized films of their solid solution, NbxTi1-xO2. Depending on their stoichiometry, these rutile NbxTi1-xO2 films can have a large absorption coefficient ≈ 17 µm-1 that is nearly independent of incident photon energy in the visible range (400-700 nm). Consequently, they appear optically black. Flat and homogenous optically black coatings like these are desirable for color isolation in flat panel displays. Films deposited by PLD were characterized for structure by XRD and Raman spectroscopy. Their optical properties were measured by spectroscopic ellipsometry and chemical states were measured with XPS. The shape of optical absorption tail curves in the band edge region (the visible spectrum for our films) is unique for specific band transitions types[7–9]. From their absorption spectra, we saw that Ti4O7 displays metallic absorption where the absorption coefficient, α varies qualitatively with incident photon energy as 𝑎𝑎(𝜔𝜔) ∝ 𝜔𝜔−2 and insulating NbO2 shows semiconducting indirect forbidden type absorption where 𝑎𝑎(𝜔𝜔) ∝ 𝜔𝜔

32. The absorption tail of NbxTi1-xO2 obeys no power

law and is instead nearly constant in the visible range. This unique absorption is the result of localized Peierls type Nb-Nb dimers in the metallic NbxTi1-xO2 phase which open an indirect forbidden transition type optical band gap in the Nb 4d orbital[6]. Other yet unknown cationic interactions exist between Nb and Ti in solid solution since the measured absorption spectra of NbxTi1-xO2 varies significantly from spectra calculated under the assumption of non-interacting cations. Although the mechanism of these cationic interactions is unclear, we have shown that the optical absorption of the NbxTi1-xO2 solid solution is both metallic and semiconducting in nature.

Blue-Black Optically Black Red-Black

Magnéli-typeTi4O7

Rutile-typeNbxTi1-xO2

Distorted rutileNbO2

c)

λ (nm)

abso

rptio

nco

effic

ient

,α(µ

m-1)

400 600 800

5

10

15

20

25

30

35T100TN25TN67N100

a)

λ (nm)

abso

rptio

nco

effic

ient

,α(µ

m-1)

400 450 500 550 600 650 7000

5

10

15

20

25

30

Titanium nitride

TN67

NbO2 (N100)

Ti4O7 (T100)

Si Fe3O4

TN25

b)

84

References [1] M. R. Querry, Optical Constants, Kansas City, 1985. [2] J. Pflüger, J. Fink, W. Weber, K. P. Bohnen, G. Crecelius, Phys. Rev. B 1984, 30, 1155. [3] D. E. Aspnes, A. A. Studna, Phys. Rev. B 1983, 27, 985. [4] A. Ishii, K. Kobayashi, I. Oikawa, A. Kamegawa, M. Imura, T. Kanai, H. Takamura, Appl.

Surf. Sci. 2017, 412, 223. [5] T. Hitosugi, H. Kamisaka, K. Yamashita, H. Nogawa, Y. Furubayashi, S. Nakao, N. Yamada,

A. Chikamatsu, H. Kumigashira, M. Oshima, Y. Hirose, T. Shimada, T. Hasegawa, Appl. Phys. Express 2008, 1, 111203.

[6] A. O’Hara, T. N. Nunley, A. B. Posadas, S. Zollner, A. A. Demkov, J. Appl. Phys. 2014, 116, 213705.

[7] M. Dresselhaus, G. Dresselhaus, S. Cronin, A. Gomes Souza Filho, 2018, DOI: 10.1007/978-3-662-55922-2.

[8] J. Tauc, Mater. Res. Bull. 1968, 3, 37. [9] J. Nakahara, K. Kobayashi, A. FujII, J. Phys. Soc. Japan 1974, 37, 1312. 3D Structural Analysis of 3D Printed Parts to Support New Anti-Counterfeiting Measures

Tanner Ricketts1, Tamas Varga1, Timothy R. Pope2, and Christopher A. Barrett2 Corresponding Author: tamas.varga@pnnl.gov 1. Environmental Molecular Sciences Laboratory, PNNL, Richland, WA, United States. 2. National Security Directorate, PNNL, Richland, WA, United States. Additively manufactured (AM) objects made by 3D printing are becoming increasingly used in many technological applications. This shift could lead to an influx of materials and devices of unknown origin flooding the globe, potentially increasing the prevalence of counterfeit goods. A thorough understanding of the chemical and structural composition of these types of objects as well as the raw materials from which they are produced yields useful information of provenance. Imaging techniques such as X-ray Computed Tomography (XCT) combined with chemical characterization by differential scanning calorimetry (DSC), pyrolysis-GCMS, and X-ray diffraction were employed to determine the microstructure and chemical composition of AM objects. This information (e.g., structural features such as porosity or grain size) is being explored for the identification of the source of the raw materials, to elucidate the additive types and content, and the method of manufacturing.

Figure 1: XCT slice images of a piece of a 3D printed cell phone case: relative porosity and density unique to specific print, and 3D maps of particulate location and distribution in each sample were revealed.

ToF-SIMS analysis on the transformation of clay-sorbed nitrogen by acidogenic bacteria Burkholderia glathei

Liuqin Huang1*, Wen Liu1, Zihua Zhu2, Hailiang Dong3, Hongchen Jiang1 1. State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430074, China; 2. Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, 99354, USA 3. Department of Geology and Environmental Earth Science, Miami University, Oxford, OH, 45056, USA Corresponding Author: huanglq1987@163.com Ammonia (NH4

+) adsorption on the surface and intercalation into the interlayer space of clay minerals can efficiently reduce the migration of NH4

+, which plays an important role in retention of NH4

+-based fertilizers in soil. As a fact, clay-sorbed NH4+ comprises a substantial part (2%-

85%) of N in soil, especially in clay-rich subsoils. Comparing to the known physicochemical parameters such as alternative cations (e.g., K) that affect stability of clay-sorbed NH4

+, microbial metabolisms may be more important as NH4

+ is a main nutrient and/or substrate for microbes that are extremely abundant and closely attached to the clays in the soil. However, the release processes and transformation mechanisms of clay-sorbed NH4

+ by microbial activity was poorly understood. More interestingly, the newly formed N species (e.g., organic N) may also associate with clay minerals, which are hardly distinguished from adsorbed NH4

+ by bulk analysis. Time-of-Flight secondary ion mass spectrometry (ToF-SIMS) is a powerful surface analysis tool, which can provide elemental, isotopic and molecular information on the clay surface where microbes attack. In this study, NH4

+ was first adsorbed by five typical soil clays, including smectite (SWy-2), smectite-illite mixlayer clays (S-I 30:70, 50:50 and 60:40) and kaolinite (KGa-1). Spectral PCA analysis based on both negative and positive revealed that the surface of raw clays (no NH4

+ sorption) was abundant with SiO/AlO-, Cl-, and Na-related clusters but was coated mainly by NH4

+- and PO-related clusters after NH4+ sorption, which was consistent with the

increase of N content in the clay minerals after NH4+ sorption as determined by elemental analysis

of bulk samples. After these NH4+-containing clays were added as the sole N source for the growth

of a common soil acidogenic bacteria (Burkholderia glathei), ToF-SIMS analysis revealed that the signal of NH4

+- and PO-related clusters that dominant on clays in abiotic controls almost disappeared, while complex organic C and N-related clusters (e.g., CH and CN clusters) were abundant on bio-reacted clays, providing direct molecular evidence that the NH4

+ was easier released by microbial attack but the released NH4

+ assimilated into organic N and closely associated with the clay minerals. The ToFSIMS results were also supported by more NH4

+ release into solution (detected by spectrophotometry) but less reduction of total N on the clay particles (detected by an elementary analyzer) after microbial metabolisms than in abiotic controls. We will further characterize chemical states of N and quantify different N species on the clay mineral surfaces using X-Ray photoelectron Spectroscopy.

86

Plant Imaging Using Delayed Extraction Time-of-Flight Secondary Ion Mass Spectrometry

Rachel Komorek1, Wen Liu2, and Zihua Zhu2, Christer Jansson2, Xiao-Ying Yu1, * Corresponding Author: rachel.komorek@pnnl.gov 1. Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory (PNNL), Richland, WA 99354, USA. 2. W. R & Wiley Environmental Molecular Science Laboratory, PNNL, Richland, WA 99354, USA.

Bacterial biofilm formation on plant roots is known to be associated with biological control and pathogenic response, however the mechanism by which plants actually associate with bacteria to elicit such beneficial effects is not well-known.[1] We present recent high resolution imaging results of dried Brachypodium distachyon (Brachypodium) seeds with and without exposure to the plant growth-promoting bacteria (PGPB) Pseudomonas fluorescens, We use time-of-flight secondary ion mass spectrometry (ToF-SIMS) delayed image extraction to achieve high mass and high spatial resolution for imaging of defined seed segments.[2] Imaging was conducted on the surfaces of three seeds prepared under different conditions: completely dry, soaked in DI water then dry, and soaked in Pseudomonas-inoculated DI water then dry. The seeds which were soaked remained in solution for 24 hours and were dried with nitrogen gas. All seeds were cut into three segments defined as the top, bottom, and brush. The seed sections were pinned down to the sample stage. Prior to inoculation, Pseudomonas was cultured in Lysogeny Broth and grown to log-phase, determined to be 5-16 hours. SIMS data were then mass calibrated and reconstructed and images were obtained for each seed section. Initial image comparison between control and Pseudomonas-inoculated seeds reveals key morphological and chemical differences, including change of hair size and features on the surface of the seed. Additionally, examination of different mass spectral peaks, such as a key nutrient choline (m/z 104, C5H14NO+), indicates the chemical composition is relevant to seed germination potential.[3] Ultimately, we have demonstrated that ToF-SIMS is capable of providing state-of-the-art quantitative and qualitative measurements with which to compare plant surface chemistry at key areas of Brachypodium seeds, which can be used to identify the relationship between seed growth and microbial community responses.[4]

References: [1] Y Bashan et al., Azospirillum-plant relationships: physiological, molecular, agricultural, and environmental advances (1997-2003). Can. J. Microbiol. (2004), 50(8), 521-77. [2] QP Vanbellingen et al., Time-of-flight secondary ion mass spectrometry imaging of biological samples with delayed extraction for high mass and high spatial resolutions, Rapid Comm. Mass Spectrom. (2015), 29 (13), 1187-95. [3] C. Böttcher, et al., Analysis of phenolic choline esters from seeds of Arabidopsis thaliana and Brassica napus by capillary liquid chromatography/electrospray- tandem mass spectrometry, J. Mass Spectrom. (2009), 44 (4), 466-76. [4] We acknowledge support from the PNNL Laboratory Directed Research and Development fund and instrument access to the DOE BER EMSL user facility under the general user proposal 50093.

Reflection Electron Energy Loss Spectroscopy for Determining Optical Constants of Actinide Surfaces

A. J. Nelson,1 S. B. Donald,1 P. Roussel2 Corresponding Author: nelson63@llnl.gov 1. Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA 94550 USA. 2. AWE, Aldermaston, Reading, Berkshire RG7 4PR, UK. Reflection electron energy loss spectroscopy (REELS) was used to characterize the optical properties of plutonium and plutonium oxides. Auger electron spectroscopy was used to identify the oxides and metal using established P1VV/O45VV line-shapes. REELS spectra were acquired with several primary electron beam energies ≤ 2 kV to validate the experimental conditions for the inelastic mean free path (IMFP) in thin oxide layers. The optical properties, as defined by the dielectric function ε, the refractive index n and the extinction coefficient k, were extracted using the quantitative analysis of electron energy loss at surfaces QUEELS-ε(k, ω)-REELS software package. [1] Using the QUEELS-ε(k, ω)-REELS software, we subtract the elastic peak from the REELS spectrum, which gave the effective single scattering cross section function IMFP•K(T) in absolute units of eV-1. The relative intensity and line-shape of the Energy Loss Function (ELF) was iteratively determined from the strength, width and energy position of Drude-Lindhard type oscillators with the final intensity rescaled to fulfill the Kramers-Kronig sum rule. Once the calculated REELS spectrum matched the acquired REELS spectrum, the optical properties were calculated and are presented in Figures 1 and 2 shown below. Comparison with previous spectroscopic ellipsometry studies [2, 3] at select wavelengths reveals that this methodology can provide an alternative means to study optical properties of surfaces.

(a) (b) Figure 1 (a) Optical constants for sputter cleaned Pu determined with QUEELS-ε(k, ω)-REELS. (b) Optical data derived from Kramers Kronig analysis of ELF data. References: [1] S. Tougaard and F. Yubero, Surf. Interface Anal. 36, 824 (2004). [2] D. T. Larson and D. L. Cash, J. Nucl. Mater. 24, 232 (1967). [3] B. Mookerji, M. Stratman, M. Wall and W. J. Siekhaus, J. Alloys Comp. 444, 339 (2007). [4] Please include any acknowledgements as the final entry in the reference list.

88

Dynamic SIMS for Materials Analysis in Nuclear Science

Paula Peres1, Alexandre Merkulov1, Seo-Youn Choi1, François Desse1, Yongqiang Wang2, Feng Ren3, Philippe Bienvenu4, Ingrid Roure4, Y. Pipon5, and L. Sarrasin5,6 Corresponding Author: paula.peres@ametek.com 1. CAMECA, 29 quai des Grésillons, 92622 Gennevilliers Cedex, France 2. Los Alamos National laboratory, US 3. Wuhan University, China 4. CEA, Nuclear Energy Division, Cadarache, France 5. Institut de Physique Nucléaire de Lyon (IPNL), France 6. Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Cadarache, France Offering extreme sensitivity, high depth and lateral resolution together with high throughput, dynamic SIMS (Secondary Ion Mass Spectrometry) proves extremely useful for a wide range of nuclear science applications: • Study of fission products behavior in irradiated nuclear fuels • Characterization of plasma facing materials in fusion devices • Investigation of long-term behavior of nuclear materials for safe waste disposal • Uranium isotope analysis on safeguards environmental samples. • Study of uranium accumulation processes in human tissues and cells.

The CAMECA IMS 7f-Auto is a versatile magnetic sector SIMS well suited for these applications. It offers depth profiling with excellent detection limits (ppb to ppm) and high depth resolution; elemental as well as isotopic information ranging from low mass (H) to high mass species (Pu and above); unique sub-μm resolution 2D and 3D imaging capabilities; as well as high throughput and automation. CAMECA also offers a Shielded IMS specifically developed for the analysis of highly radioactive samples.

In the example below, SIMS imaging measurements were performed on a cerium dioxide (CeO2) disk sample annealed at 1400°C for four hours after xenon implantation. CeO2 is usually considered as a non-radioactive surrogate of UO2 ceramics to simulate the properties of nuclear fuels during irradiation processes or long-term storage.

Different applications covered by the CAMECA IMS 7f-Auto for materials analysis in nuclear science will be presented.

Figure 1 SIMS ion imaging of a CeO2 sample annealed at high temperature (left: 140Ce, right: 139La).

0%

Visualizing Li metal interaction with LiCoO2 thin film cathodes using in situ TEM

Zhenzhong Yang,1 Phuong-Vu Ong,1 Yang He,2 Le Wang,1 Wu Xu,3 Timothy C Droubay,1 Chongmin Wang,2 Petr V Sushko,1 Yingge Du1,* Corresponding Author: Email: yingge.du@pnnl.gov 1Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, United States 2 Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352, United States 3 Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, WA 99354, United States The formation of unwanted lithium dendrites can cause performance degradation and device failure in lithium rechargeable batteries. Thus, understanding the atomic scale reaction processes between lithium metal dendrites and cathode materials can not only provide insights into the failure mechanisms, but also guide the materials design principles. In this study, using atomically resolved in situ transmission electron microscopy (TEM), we directly image the lithium dendrite effect on differently oriented, epitaxial LiCoO2 (LCO) thin film cathodes. While our results demonstrate that the chemical reaction between Li and LCO is spontaneous and prompt, leading to Li2O and Co metal formation in the fully reacted regions, a clear region characterized by CoO as a reaction intermediate is identified close to the reaction front. Moreover, high density of antiphase grain boundaries (a-GBs) are found at the reaction forefront, most likely due to the large volume expansion upon irreversible lithiation. Meanwhile, these a-GBs act as the fast Li diffusion channel surrounding the nano grains, accelerating the long range Li transport and local topotactic phase transformation from LiCoO2 to CoO. Uranium Particles Analysis and Imaging Using ToF-SIMS for Source Identification Juan Yao1, Zihua Zhu2, and Xiao-Ying Yu1

Corresponding Author: xiaoying.yu@pnnl.gov 1 Pacific Northwest National Laboratory, Earth and Biological Sciences Directorate, Richland, WA. 99354, USA 2 Pacific Northwest National Laboratory, W. R. Wiley Environmental Molecular Science Laboratory, Richland, WA. 99354, USA Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is a highly surface sensitive analytical tool. It offers excellent limits of detection (LODs) of part per million with sub-micron spatial resolution. Besides determining isotopic ratios of radioactive materials, ToF-SIMS has the advantage of providing full mass spectra with m/z up to 2000 Da, allowing the detection of chemical signatures in a material. This latter feature is very attractive to identify the source of uranium and other radioactive materials in single particles. We analyzed three different NIST standard reference materials with varied concentrations of uranium in this study. Samples are in the form of glass wafers and particles deposited on a substrate. By applying spectral principal component analysis (PCA), the SIMS mass spectra obtained from the same type of NIST sample show consistent features; regardless of the sample form. Furthermore, a blind test was conducted using a mixture consisting of particles from all three NIST materials. Our spectral PCA results illustrate that ToF-SIMS can be a useful tool to differentiate particles of different origins and potentially applicable for signature identification in single particles. In addition, scanning electron

90

microscopy (SEM) was applied to complement the SIMS imaging for correlative analysis [1]. It is beneficial to use SEM to obtain particle morphological information. However, SEM lacks the sensitivity in single particle elemental analysis compared to ToF-SIMS. Our work demonstrates that ToF-SIMS is a powerful tool for analysis of individual radioactive particles to fulfill nuclear safeguards and forensic missions. References: [1] X.-Y. Yu, et al., Imaging liquids using microfluidic cells, Micro. & Nano. 15(6) (2013), 725-44. Engineering correlation effects of 5d transition metal oxide SrIrO3 via artificially designed superlattices Jishan Liu1, Zhengtai Liu1, Cong Fan1 and Dawei Shen1 Corresponding Author: jishanliu@mail.sim.ac.cn 1. Shanghai Institute of Microsystem and Technology Information (SIMIT), Chinese Academy of Sciences (CAS), Shanghai, China Novel interplay of spin-orbital coupling and electron correlation in perovskite strontium iridates recently emerged as new paradigm for correlated electron physics. Furthermore, its exotic physical properties can be manipulated by tailoring superlattice structures. In this poster, we present the structure and properties of OMBE grown perovskite [(SrIrO3)m/SrTiO3] superlattices, where m=1/2, 1, 2, 3 ... ∞. The films are grown in a layer-by-layer fashion as revealed by RHEED, and the resulting surfaces are atomically flat as determined by AFM. XRD and TEM measurements shown in Fig. 1 further demonstrate the designed crystalline structures and nearly atomically-sharp interfaces. With the dimensionality decreasing, a Mott-type metal insulator transition (MIT) emerge in the experimentally realized superlattices, as shown in Fig. 2. By analyzing the photoemission spectra, we assign the increasing effective electron correlation caused by dimensionality decreasing as the dominating origin for this MIT. Our finding highlights the importance and effectiveness of controlling the correlation effects and tailoring the exotic states in 5d iridates by designing different superlattices/heterostructures.

Fig. 1 Structure characterization of the superlattice films.

Fig. 2 Temperature dependence of resistivity of the superlatttice films

References: [1] Z. T. Liu, M. Y. Li, Q. F. Li, J. S. Liu, W. Li, H. F. Yang, Q. Yao, C. C. Fan, X. G. Wan, Z. Wang and D. W. Shen, Direct observation of the dirac nodes lifting in semimetallic perovskite SrIrO3 thin films, Sci. Rep. 6(2016), 30309.

[2] C. C. Fan, Z. T. Liu, S. H. Cai, Z. Wang, P. Xiang, K. L. Zhang, W. L. Liu, J. S. Liu, Y. Zheng, D. W. Shen and L. X. You, Reactive molecular beam epitaxial growth and in situ photoemission spectroscopy study of iridates superlattices, AIP Adv. 7(2017), 099901.

92