QUANTITATIVE-ANALYSIS BY XPS USING THE MULTILINE APPROACH

An efficient method for quantitative XPS analysis is the so-called mul tiline approach. This method does not require standards, it takes into account the instrumental and matrix effects and it derives quantitati ve information from statistical analysis of all photoelectron intensit ies visible in the spectre. One can expect the reliability of this app roach to be better than the reliability of methods involving uncorrect ed relative sensitivity factors. This paper summarizes recent improvem ents in the multiline approach. In particular, a new expression for th e universal energy dependence of the inelastic mean free path is curre ntly used. Furthermore, the statistical analysis has been modified in order to account properly for the error in the countrates. Finally, a database with physical constants has been added (photoionization cross -sections, asymmetry parameters, binding energies, etc.) to avoid erro rs of polynomial approximations. The modified algorithm of the multili ne approach was applied to photoelectron intensities measured for AuCu alloys in four laboratories. Surfaces of these alloys were sputtered with 2 keV Ar+ ions, because at this energy the selective sputtering e ffects are expected to be negliible. Very consistent results were obta ined. The average deviation from the bulk surface composition was foun d to be equal to +/- 3.2 at.%. Extensive software implementing the des cribed version of the multiline approach is presently being developed.