Quantitative AES IX and quantitative XPS II: Auger and x-ray photoelectron intensities and sensitivity factors from spectral digital databases reanalysed using a REELS database

An extension has been made of previous analyses of peak area intensities for elemental spectra in digital Auger and x-ray photoelectron databases. The intensities, instead of being analysed after removal of a background derived from the Tougaard Universal cross-section, are now analysed after removal of the extrinsic characteristic loss background calculated by deconvolving the relevant angle-averaged reflected electron energy-loss spectroscopy (REELS) spectrum. The angle-averaged REELS data for each element are calculated from a digital REELS database using a recently defined scaling of the measured characteristic losses from the elastic peak. The new background removal procedure leads to an improvement in the correlation between experiment and theory for intensities in both AES and XPS. Analysis of these correlations shows that a systematic divergence remains for each element, which is the same for XPS as for AES. This divergence is attributed to an inadequacy either of the angle-averaged REELS method or of the material-to-material dependence of the TPP-2M equation used in the calculation of the inelastic mean free paths. Correction for this is possible in a new matrix-less quantification formulation using average matrix sensitivity factors. This leads to correlations between experiment and theory with scatter factors of X/divided by 1.08 and x/divided by 1.11 for AES and XPS, respectively, for a wide range of elements and peaks. These scatter factors are much better than for previous correlations and underpin the choice of formulae to calculate the relevant theoretical intensity predictions. These calculations lead directly to values of average matrix sensitivity factors, appropriate for use with spectrometers giving true spectra or with those spectrometers that may be calibrated to provide such spectra. (C) Crown Copyright 2001. Published by John Wiley & Sons, Ltd.