An experimental study of the factors that effect ion desorption yields

Abstract

Many models of photon-stimulated desorption (PSD) predict that the desorption yields resulting from the formation of two-hole or two-hole, one-electron states will increase as the effective hole–hole interaction Ueff increases and the covalent interaction V decreases. In order to investigate this effect in a systematic manner, we have studied PSD of H+, CH+3, and F+ ions from solid Si(CH3)4−nFn (n=0–4) using synchrotron radiation in the energy range 15–40 eV. The trends of the PSD desorption yields of H+, CH+3, and F+ as a function of n were determined. There is a dramatic increase in the H+ and CH+3 PSD yields as n becomes larger, while the F+ yield increases slowly as a function of n. In order to explain the results, we propose a model which considers the manner in which Ueff and V depend on the number of –CH3 and –F ligands.