PNNL

Abstract

The relative intensities of XPS core-levels, scaled by their photoionization cross-sections, are regularly used to determine sample atomic composition. Cross-sections, however, give the intensity to all possible final states for the core ionizations, not just to the main peak. This includes all intrinsic satellite structure (shake states, and, for open shell systems, the different ionic multiplets). In practice, for solids, this is usually experimentally impossible to determine accurately, because such satellite structure sits on the inelastically scattered electron background, and cannot be easily separated. So, usually only the intensity of the main peak is used. This limits the ultimate possible accuracy of XPS composition determination. The purpose of the present paper is to examine the contributions that a theoretical analysis of losses of intensity can make to improving quantitation. For an MgO single crystal we show that the correct stoichiometry of 1:1 can be recovered using the theoretical analysis of the experimental MgO peak ratio intensities.