Electron stimulated desorption thresholds for excited atoms desorbed from alkali-halides

Abstract

Abstract We have investigated the thresholds for the generation of desorbed excited alkali atoms under electron bombardment for LiF, KCl and KBr in the energy range from 10 to 120 eV, and from room temperature up to 450°C. The dependence of the yield of excited atoms on the electron energy shows features which are in good agreement with the excitation energies of alkali core-excitons in the alkali-halide crystal. This suggests the production of an alkali core-exciton as an initial step for the desorption of excited alkali metal atoms under electron bombardment. The dependence of the yield of excited alkali atoms on either the temperature of the crystal or the electron density in the irradiated surface area gives additional support for that model.