Electron Transfer Processes And Energy Losses In Scattering Of Ions In Gaseous Targets And On Surfaces

This dissertation is aimed at investigation of electronic energy loss and charge transfer process in particle - surface scattering performed in LCAM,Pads,and studies of charge transfer process in ion-atom collisions performed in Lanzhou University, Lanzhou.The present dissertation is arranged as follows:The concepts and theoretical model of ion - surface/atom interaction are presented in chapter 1.The main apparatus used in this work is presented in chapter 2.In chapters 3 and 4,we present the results of an experimental study of surface channeling and stopping of hydrogen,helium and fluorine ions in grazing scattering on Au surfaces at ion energies between 1 keV and 4 keV.Energy loss depending on different azimuthal orientations has been analyzed,and multi-peak structures in the energy spectra are observed and attributed to different trajectory classes.The, trajectory simulation involving electronic corrugation of the surface has been performed by J.Valdes and the simulated results are in good agreement with the experimental data.Charge transfer process of Li⁺ ions scattered off the clean Au(110) surface and Ag ultra-thin layer supported on Au(111) is presented in chapter 5.Neutral fraction of Li⁺ ions scattering off the clean Au(110) surface has been measured for different parameters(incident energies,exit angles and azimuthal orientations).Highly efficient neutralization on noble metals with high work functions contradicts our traditional resonant charge transfer(RCT) mechanism.Modified RCT involving new, neutralization processes occurring at a much short internuclear distance has been performed and compared with our data.The growth of Ultra-thin Ag film on Au(111) was studied by STM,and neutral fraction of Li⁺ ions scattering off an ultra-thin Ag film supported on Au(110) has been performed.The neutral fraction decreases monotonically with the increase of the incident energies or exit energies and shows no difference from the Ag bulk.The model calculation shows a better agreement with the experimental data compared with the results based on the conventional jellium model.The charge transfer of MeV C^q+ in collision with Ar has been studied and presented in chapter 6.We get empirical scaling laws for the ratios of n-fold ionization corresponding to single electron loss by the projectile.It is observed that the ratios of n-fold ionization associated with single electron loss,the ratios of multi-ionization associated with single electron loss to pure single electron ionization and the ratios of multi-ionization associated with single electron capture to pure single electron capture are all dependent strongly on the charge states of the projectile and vary significantly in different reaction channels with the increasing impact energy in the present experiment.The ratios of multi-ionization associated with single loss to pure single ionization present an interesting oscillatory structure.Finally,modified theoretical model of over-barrier model was developed and used to treat charge transfer of multi-charged ions in collisions with the H and He target atoms,as shown in chapter 7.It is very simple for experimental physicists to estimate the cross section quickly.