Effects of differentiation on peak intensity in direct Auger spectra

A companion paper in this issue of Surface and Interface Analysis (Surf Interface Anal. 2021;1-6. doi: 10.1002/sia.7029) discusses corrections for the effects of analyzer modulation on peak intensity in derivative Auger spectra. Today, most Auger spectra are acquired in the direct mode, E center dot N(E), and derivatives are taken using a computer program to measure peak intensities (peak-to-peak heights) with the background suppressed, for ultimate quantification. In taking a derivative, there is sometimes a choice of the algorithm used for taking the derivative, but the most common method is to use the Savitzky-Golay algorithm. In using the Savitzky-Golay algorithm, there is also a choice in the number of data points used in the differentiation. To improve quantification, Martin Seah suggested using relatively large Gaussian broadening in the differentiation process to reduced effects of line shape differences in measuring signal intensities, as often occur due to chemical effects on spectra. This paper shows the effects of the number of points used with the Savitzky-Golay algorithm in taking the derivative on peak-to-peak heights in derivative Auger spectra and how dynamic background subtraction can be used to obtain Auger peak area values independent of the broadening of spectra caused by such differentiation.

Automated summary

This paper discusses corrections for the effects of analyzer modulation on peak intensity in derivative Auger spectra, emphasizing the use of the Savitzky-Golay algorithm and dynamic background subtraction for improved quantification. By studying the number of data points used with the algorithm in taking the derivative, the paper shows how to obtain Auger peak area values independent of the broadening of spectra caused by differentiation.