Desorption Yields and Irradiation-Condition Dependence of Layer-by-Layer Removal for KBr(001) Surface Stimulated by Electrons

Abstract

Desorption yields obtained from a KBr(001) surface irradiated by 1.5-3-keV electrons have been measured via layerby-layer mode removal. The yields are obtained from the inverse electron fluences required to remove the monolayer, which are measured from the specular intensity oscillations of 15-keV protons incident on the surface with small angles (≤1°). The desorption yield dependence on electron energy and beam current density (range : ≤100 nA cm-2) of the incident electrons has been measured while varying the sample temperature (350-470 K). The electron energy dependence is weak, and there is no apparent beam current density dependence. However, the initial half-period of the intensity oscillation curve tends to extend, and the oscillation shifts to higher electron fluence with increasing electron energy, electron beam current density, and decreasing sample temperature. A possible explanation for the aggregation is provided via attributing this result to the existence of aggregated F centers.