Theoretical Study Of The Glancing Scattering And The Electron Emission Of Energetic Ions Incident On Solid Surface

The interaction of energetic ions with solid material has been a very important research field in the past few dedades. Especially, the studies of the ion-surface scattering and the aspects related to it have received much attention. Research in this field not only focuses on some fundamental problems, but also has resulted in astonishing progress in the applications, such as surface modification, surface structure analysis and the thin solid film deposited by the atom sputtering. In the recent few years, the development of accelerator technology has opened up the possibility of producing molecular ions and ion clusters in laboratories, has allowed us to probe the different dynamic of particle-matter interaction, and has promoted the utility of ion beam technology in the applications of material science and the inertial confined fusion. In this work, the grazing scattering process of the energetic ions on solid surface has been investigated. In this extreme geometry, as an energetic ion approaches solid surface under a grazing angle, it will be first attracted by a long-distance induced electric field due to the excitations of the electron gas and subsequently reflected by a short-ranged repulsive force of topmost atoms located in the first surface layer. By studying the scattering trajectory and the energy loss of the ion, one can obtain the corresponding information both about the ions and the solid surface.Based on the dielectric response theory and the specular reflection model, a theoretical model is given to describe the grazing scattering of ions incident on a solid surface, and the interaction of H+ ions and the surface is calculated. A local-field correction (LFC) dielectric function and a local frequency-dependent dielectric function with a damping factor have been adopted respectively, in low- and high-velocity regimes. The scattering trajectories and the energy losses are obtained and compared well with the experimental results. It is observed that the energy losses decrease slowly with the increasing incident angles for low velocity ions, whereas swift ions lose more energy with the increase of the incident angles.After the simulation of H+ ions, a further investigation has been taken for heavy ions glancing scattering from solid surface. Considering the distribution of the electron bound to the projectiles, as a correction of the Brandt-Kitagawa model, a planar charge distribution is first put forward which is a guarantee of the continuity of the potential induced by the ion. As for the different charge exchange processes near the surface for slow and swift projectiles, a double exponent model and a linear interpolation combined with a velocity-dependent electron-stripping model are adopted in the simulations, together with the plasmon pole approximation (PLA) and LFC dielectric functions are used. Thus, the analytical expressions for the position-dependent stopping power and the surface image potential have been obtained. The projectile trajectories and the energy losses, dependent on the charge state of the ions and the incident angle, are calculated and compared with the corresponding experimental results. The calculated results demonstrate that: in the low velocity regime, the energy loss exhibits a monotonic increase with the increasing charge state, and shows a slight decrease with the increasing incident angles; on the other hand, high velocity ions mayapproach the topmost layer much closer than slow ions as the incident angles increase so that the contribution of the inner-shell electrons to the stopping power should be included giving rise to a small increase of the energy loss for the incident angles which approach to the critical angle. Moreover, including the exchange-correlation interaction among the electrons, the adoption of the LFC dielectric function has done a good job in describing the perturbation given by the slow projectiles and breaks through the limitation of RPA (random phase approximation) dielectric theory.Using the dynamic interaction potential given by the study of heavy ion...