QUANTITATIVE AES - V - PRACTICAL ANALYSIS OF INTENSITIES WITH DETAILED EXAMPLES OF METALS AND THEIR OXIDES

A study is made of the metal and oxygen Auger electron intensities of a range of metals and their stoichiometric oxides from the high-resolu tion digital Auger electron database. The changes in peak shape for th e oxygen Auger electrons is analysed and it is shown that, for a const ant oxygen peak area, the direct spectrum peak heights and the differe ntial peak-to-peak intensities each scatter over factors of 3 and 5, r espectively. However, by broadening the spectra with a Gaussian functi on of up to 20 eV width, the scatters in the differential peak-to-peak heights can be reduced to a relative standard deviation of similar to 5%. The broadening and differential method is not as accurate as a fu ll analysis of peak area with all the necessary corrections, but it is simple and rapid and is about five times more accurate than existing simple differential procedures. The use of the broadened differential peak-to-peak intensities will need new sensitivity factors for quantif ication, which may be derived from traditional values and the data pre sented here. The relative intensities of the L2,3M2,3M2,3, L2,3M2,3M4, 5, L2,3M4,5M4,5 metal peaks for Ti to Zn in the metallic and oxide sta tes are also analysed and are shown to correlate well with theoretical predictions. However, small differences for the areas of these peaks between the metallic and oxide states are seen, leading to a relative standard deviation of 2.9% in the intensity ratios. These differences correlate with a simple model for the effect of oxygen on the effectiv e number of valence electrons available in the metal M-4,M-5 level con tributing to the relevant Auger electron transitions. This results in a small change in the relative intensities of the metal peaks on oxida tion. Measurements for the oxygen Auger electrons show a complementary effect. These results show that the relative area of a single intense peak in the multiplet structures for the metals and for oxygen varies by typically 2.9% and 6.7%, respectively, when normalized against the respective total peak areas, These uncertainties add to the overall u ncertainties in quantifying data in AES analysis where a single peak i n the group is used, e.g. in analysis using traditional differential s pectra. (C) 1998 John Wiley & Sons, Ltd.