U.S.-Japan Cooperative Research: Interactions of Swift Charged Particles with Valence Electrons Near Surfaces

该奖项为美国田纳西大学物理与天文学系的Joachim Burgdorfer教授和Stuart B Elston教授以及日本京都大学工程系量子物理小组在Michi-hiko Mannami教授的领导下开展的为期两年的合作研究项目提供支持。该项目的目的是对表面附近的快速带电粒子与价电子的碰撞相互作用进行理论和实验的合作研究。从清晰明确的表面以掠射角度散射提供了在大冲击参数下研究碰撞过程的机会，从而加强了与表面附近价电子的相互作用，同时抑制了离子核的贡献。该项目将首先包括理论和实验研究在掠角离子表面碰撞中喷出的护航电子的能量和角度分布随弹丸电荷状态和速度以及表面结构和组成的函数。其次，将发展散射离子反射的计算机模拟，特别强调电子抛射态的同步演化和价电子的动态响应。最后对通道快速离子产生的护卫队电子的产率和角分布进行了理论和实验研究。京都大学和田纳西大学的研究小组的工作有很强的重叠，在理论和实验方面都有互补的能力。例如，美国的研究小组在固体中电子输运的蒙特卡罗模拟方面拥有丰富的数值经验，而京都的研究小组则开发了固体表面离子散射的模拟代码。这个项目应该提供关于离域电子对激发过程的贡献，关于传导电子的集体响应及其对二次电子发射的影响，更广泛地说，关于非弹性碰撞过程作为表面诊断工具的有用性的详细新信息。

This award provides support for a two year cooperative research project between Professor Joachim Burgdorfer and Professor Stuart B Elston, Department of Physics and Astronomy, University of Tennessee, and the Quantum Physics Group at the Department of Engineering, Kyoto University, Japan, led by Professor Michi-hiko Mannami. The purpose of the project is to undertake a collaborative theoretical and experimental study of the collision interactions of fast charged particles with valence electrons near surfaces. Scattering from clean well defined surfaces at glancing angles provides the opportunity to study collision processes at large impact parameters, thereby accentuating interactions with valence electrons in the proximity of the surface while suppressing contributions from ionic cores. The project will involve firstly a theoretical and experimental investigation of the energy and angular distributions of convoy electrons ejected in glancing angle ion-surface collisions as a function of projectile charge state and velocity, and surface structure and composition. Secondly a computer simulation of the reflection of scattered ions will be developed, with particular emphasis on the simultaneous evolution of electron projectile states and the dynamical response of the valence electron. Finally a theoretical and experimental investigation of the yield and angular distribution of convoy electrons produced by channeled fast ions will be carried out. There is strong overlap between the work of the groups at Kyoto University and the University of Tennessee, with complementing capabilities in both theory and experiment. The group in the US, for example, have extensive numerical experience in Monte-Carlo simulations for electronic transport in solids, where as the Kyoto group have developed a simulation code for ionic scattering from solid surfaces. This project should provide detailed new information on the contribution of delocalized electrons to excitation processes, on the collective response of conduction electrons and its influence on secondary electron emission and, more broadly, on the usefulness of inelastic collision processes as a tool of surface diagnostics.