Quantitative AES and XPS: Tests of Theory Using AES and XPS Databases with REELS Background Subtraction

Abstract

A brief review is given of the status of the tests of quantitative AES and XPS theory using three databases of true [1–5] spectra for AES [6-9], XPS [8-10] and REELS [10-12], respectively. For quantitative analysis by AES and XPS, it is important to test the theory and to use the correct sensitivity factors. We develop our previous analyses of peak area intensities for elemental spectra in digital Auger and X-ray photoelectron databases measured using a fully calibrated spectrometer. The intensities, instead of being analysed after removal of a Tougaard background are now analysed after removal of the extrinsic characteristic loss background by deconvolving the elemental angle-averaged reflected electron energy loss spectra (REELS). The photoelectron spectra now show clear intrinsic shake-up intensities, reduced to around 30% of the total peak intensities. A comparison of theory and experiment within a new matrix-less quantification formulation, using average matrix sensitivity factors, an example of which is shown in Fig 1, leads to correlations with rms scatters of 8% and 11% for AES and XPS, respectively, for a very wide range of transitions. This gives formulae and values of sensitivity factors, appropriate for use with spectrometers calibrated to give true spectra.