Electron emission and surface etching by slow and medium highly charged ions on HOPG surface

Highly charged (129Xeq+, q = 10–30) ion-induced secondary electron emission and formation of nanostructure on the surface of highly oriented pyrolytic graphite (HOPG) have been studied on the 320 kV ECR platform for Highly Charged Ion Beam at IMP-CAS, Lanzhou. The experimental data of the total secondary electron yields are used to separate contributions of kinetic and potential electron yields. The estimated kinetic electron yields are about 17 and 35 electron/ion by ions with kinetic energies of 600 keV and 5 MeV, respectively. The potential electron yield increases linearly with increasing potential energy of the incident ion. The total electron yield, however, does not depend significantly on kinetic energy. AFM analysis of the HOPG surface bombarded with Xe30+ ions revealed regular hillock like nanostructure. The relationship between hillock size (height and width) and ion’s energy (including potential energy and kinetic energy) shows the same trend with the total electron yield which increases with potential energy and is independent on incident kinetic energy.