QUANTITATIVE AES .4. ACCURACY OF THE NUMERICAL EVALUATION OF PEAK AREAS IN AES USING THE UNIVERSAL TOUGAARD BACKGROUND SUBTRACTION METHOD

A study is made of the Tougaard background subtraction method for homo geneous materials for determining the true peak area in Anger electron spectroscopy (AES) where the peak structure extends over a wide energ y range and where knowledge of the true characteristic loss background is unavailable. The effects of increased intensity in the inelastical ly scattered background are analysed using a model spectrum with the b ackground subsequently removed using the Tougaard Universal function b ut with various values of the Tougaard parameters B and C. It is shown that the full peak areas depend on the value of B/2C. The analysis is then extended to Auger electron peaks on a power law cascade backgrou nd. By a suitable procedure the sensitivity of the area to the value o f B/2C mag be reduced. Furthermore, by using the area of the highest e nergy Auger electron peak, on its own, or by using area ratios for ele ments, the errors are reduced to below 2%. It is recommended that for absolute intensities using theoretical cross-sections the full area wi th the universal values of B = 2866 eV(2) and C = 1643 eV(2) should be used, whereas for quantitative AES with relative sensitivity factors the partial area of the highest energy peak analysed with the same val ues of B and C is a better measure.