Valence-level photon-stimulated desorption of H+ from solid Si(CH3)4

Abstract

Results of photon-stimulated desorption (PSD) measurements of H+ from solid Si(CH3)4 in the photon energy range 15-40 eV are presented. The H+ PSD spectrum has a weak threshold at 17(±0.2) eV and a stronger threshold at 21.5(±0.5) eV. The H+ desorption threshold at 17 eV is interpreted in terms of excitation of an inner valence 4a1 (Si 3s/C 2s) electron to an unoccupied orbital (u). This excited state decays to 1t1−2u or 5t2−2u final states resulting in C-H and Si-C bond breaking, respectively. The desorption threshold at 21.5 eV is due to excitation of an inner valence 3t2 (C 2s) electron to an unoccupied orbital, which decays to a 1t1−2u final state, resulting in C-H bond breaking.