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<<   April 2014   >>
Sunday, April 13
Monday, April 14
Tuesday, April 15
Wednesday, April 16
Seminar 4/16/2014 - Robert Kolasinski, Sandia National Laboratories: Ion Scattering as a Probe of the Atomic-Scale Behavior of Hydrogen on Surfaces
Abstract: Directly detecting the atomic-scale behavior of adsorbed hydrogen is notoriously difficult, and represents a long-standing challenge in surface science. Nevertheless, how hydrogen interacts with metal surfaces is a key problem that affects a variety of technologically important systems, including structural materials for hydrogen energy infrastructure, fuel cells, catalysts, and plasma-facing materials for magnetic fusion energy. To provide insight into some of the materials problems that arise in these applications, we use low energy ion scattering (LEIS) and direct recoil spectroscopy (DRS), unique surface analysis techniques that directly detect adsorbed hydrogen and provide isotopic sensitivity. In our recent work at Sandia, we applied LEIS to examine the atomic-scale behavior of hydrogen on single crystal surfaces in a high-purity vacuum environment. Our basic approach bears many similarities to molecular beam scattering techniques commonly used to study combustion and plasma processes. We use an ion gun to bombard surfaces with He+ and Ne+ at energies < 5 keV, and subsequently detect the scattered and recoiled particles. From this information one can determine the structure and composition of the first few atomic layers of a surface. In this talk, I will provide an overview of the physics that underlies LEIS, along with our recent advances to directly detect adsorbed hydrogen [1]. In addition, I will describe our efforts to more accurately model atomic collisions that occur during scattering [2], a key step needed to extract structural information from LEIS. I will also highlight our recent measurements of the atomic-scale binding configuration of hydrogen to Be and W, two materials of interest as plasma-facing surfaces for magnetic fusion energy.

[1] R. D. Kolasinski, N. C. Bartelt, J. A. Whaley, and T. E. Felter, Phys. Rev. B 85 (2012) 115422.
[2] R. D. Kolasinski, J. A. Whaley, and R. Bastasz, Phys. Rev. B 79 (2009) 075416.

Bio: Robert Kolasinski is a senior member of the technical staff in the Hydrogen and Metallurgical Science Department at Sandia National Laboratories, in Livermore, CA. While at Sandia, Rob’s research efforts have focused on hydrogen interactions with surfaces, low energy ion beam analysis, and plasma-material interactions. Rob received M.S. (2001) and Ph.D. (2007) degrees from the California Institute of Technology in mechanical engineering. While at Caltech, he studied ion-surface interactions in plasma propulsion systems as part of a collaboration with the Advanced Propulsion Group at the NASA Jet Propulsion Laboratory.

All seminars are held on Wednesdays from 12:00 noon-1:00 p.m. in the Bowen Hall Auditorium Room 222. A light lunch is provided at 11:30 a.m. in the Bowen Hall Atrium immediately prior to the seminar.
Bowen Hall Auditorium  ·  12:00 p.m. 1:00 p.m.
Thursday, April 17
Friday, April 18
Saturday, April 19