Electron and photon stimulated desorption of positive ions from alkali halide surfaces

Abstract

We have observed desorption of positive ions from alkali halides stimulated by low energy electron and photon bombardment. Our experiments include the first measurements of electron stimulated desorption (ESD) of Na + from NaCl and the first measurements of photon stimulated desorption (PSD) of positive ions from NaCl and LiF. The energy dependence data indicate that the initial onset for Na + ejection by ESD occurs at the excitation threshold of the Cl(3s) core level. Similarly for the PSD of positive ions from NaCl and LiF we can relate incident photon beam energy dependent ion yields with the production of substrate core holes. The data provide insight into the mode of initial energy transfer to the solid which leads to desorption. ESD and PSD ion yields were measured to be on the order of 10 −7 ions per incident electron or photon.