Quantitative XPS I. Analysis of X-ray photoelectron intensities from elemental data in a digital photoelectron database

An analysis of the correlation of theoretical predictions for photoelectron intensities is made with experimental data from an XPS digital database fo r 46 solid elements measured using a spectrometer with calibrated intensity and energy scales. This analysis covers single element samples measured fo r Al and Mg K alpha X-rays. The spectral data are for widescans at 1 eV ene rgy intervals with kinetic energies from 200 to 1506 eV using Al X-rays and to 1273 eV using Mg X-rays. In addition are narrow scans around the photoe lectron peaks at 0.1 eV energy intervals. All spectra have the instrument i ntensity/energy response function removed so that the peak areas are propor tional to the number of electrons emitted per steradian per incident Ka pho ton. Correlations are made for the ionisation cross sections of Scofield an d the inelastic mean free paths given by the TPP-2M formula. The correlatio ns are excellent, apart from a factor which may be associated with the back ground removal arising from the use of the Tougaard Universal cross section . These correlations lead directly to pure element relative sensitivity fac tors suitable for quantitative analysis. General equations are also provide d to extract values for a new form of relative sensitivity factor for an av erage matrix. These average matrix relative sensitivity factors lead to sim pler equations involving matrix factors that are effectively unity instead of the traditional values in the range 0.3 to 3.0. (C) 2001 NPL. Published by Elsevier Science BY. All rights reserved.