Dependence of ESCA signal intensities of ionic compounds on chemical environment

Abstract

Variation in ESCA signal intensities for ionic compounds is interpreted in terms of the dependence of photoelectron escape probability on the immediate environment of the emission center. A model has been developed to estimate this escape probability by the fractional solid angle not blocked by the nearest neighbors of the emission center. A linear correlation is found between the normalized intensity ratios for simple alkali halides and the fractional escape solid angle ratios. Absolute intensity measurements have been carried out for alkali perchlorates and alkali chlorides. The chlorine signal intensities were constant for perchlorates but decrease steadily from LiCl to CsCl. These observations are consistent with the chlorine atom in the perchlorate groups always being surrounded by four oxygens; therefore its fractional escape solid angle is independent of the compound.