Chemical Physics Seminar
Electronic Stopping under Proton Irradiation: Understanding Electronic Excitation Dynamics using First-Principles Theory
Yosuke Kanai, Department of Chemistry, University of North Carolina at Chapel Hill
Electronic stopping describes the transfer of energy from a highly-energetic
charged particle to electrons in a material. This process induces massive
electronic excitations through interaction of the material with the highly localized
electric field from the charged particle. Understanding this phenomenon in
condensed-matter systems under proton irradiation has implications in various
modern technologies, ranging from nuclear fission/fusion reactors, to
semiconductor devices for aerospace missions, to cancer therapy based on
proton beam radiation. Although the energy transfer rate is often modeled using
approximated analytical theories such as Bethe theory, we discuss numerical
simulations of this quantum dynamical process using first-principles electronic
structure theory, which allows us to capture the detail quantum-mechanical
nature of this process. The first-principles simulations, based on our recentlydeveloped
large-scale real-time time-dependent density functional theory (RTTDDFT)
approach, provide a detailed description of how electrons are excited
through non-equilibrium energy transfer from protons on the attosecond time
scale. We apply this computational approach to the important case of liquid water
under proton irradiation. Our work reveals several key features in the excitation
dynamics at mesoscopic and molecular levels for deciphering water radiolysis
mechanism under proton irradiation.
Bio:
Yosuke received his Ph.D. in Theoretical Chemistry from Princeton University with Prof.
Annabella Selloni and Prof. Roberto Car, and he was a BNNI Post-doctoral Scholar at
the University of California at Berkeley, working with Prof. Jeffrey C. Grossman
(currently at MIT). He subsequently worked at Lawrence Livermore National Laboratory
as a Lawrence Fellow in Condensed Matter and Materials Division prior to joining the
University of North Carolina at Chapel Hill as an assistant professor in Department of
Chemistry. His research group's focus is on investigating dynamical phenomena in
materials and condensed phase systems by developing and applying computational
methods based on first-principles electronic structure theory for large systems.