Studies on the Core-level-excitation-induced Ion Desorption from Solid Surfaces.

Abstract

The core-level-excitation-induced ion desorption from surface is investigated. Two studies using electron-ion coincidence spectroscopy are shown. On Si(100)/H2O surface, it is shown that ion desorption is mainly induced by the shake-up/off excitation accompanying the Auger decay when the photon energy is near the O1s threshold. At a photon energy higher than the shake-up threshold, most of ions desorb resulting from the shake-up excitation accompanying the core-excitation. In both cases, the desorption is induced by the multi-hole final state. On ice surface, the kinetic energy of O1s photoelectrons gives the highest coincidence yield of H+ desorption is shifted by about −0.7 eV compared to the O1s peak observed in the conventional core-level photoelectron spectroscopy. It is ascribed to a core-level shift in the O1s level from which hydrogen ions desorb.