The energy loss of medium-energy He+ ions backscattered from a Cu(100) surface

Abstract

A model is presented for the shape of the surface peak in the energy spectrum of backscattered ions in a channeling and blocking experiment. The elastic energy loss distribution of the ions is calculated by use of Monte Carlo simulation. The inelastic energy loss distribution is calculated by use of data obtained from gas phase ion-atom collisions. The model for the shape of the surface peak is applied to the analysis of energy spectra of 175 keV He+ ions backscattered from a Cu(100) surface. It is found that, under channeling and blocking conditions, the inelastic energy loss in surface layers can be almost three times higher than under normal (i.e. random-incidence and -detection) conditions. It is therefore concluded that the inelastic energy loss depends strongly on the impact parameter of the collision.