The Detection of Low Intensity Peaks in Energy Dispersive X-Ray Spectra From Particles
John A. Small
A critical step in the processing of energy dispersive EDS x-ray spectra from the automated scanning electron microscopy, [ASEM], analysis of particles is the detection and identification of elemental peaks. Since there are often several hundred to several thousand spectra for each ASEM analysis, it is important that this step operate rapidly and with a minimum of interaction between analyst and the program. For peaks with large peak-to-background P/B ratios most peak-find or peak-fitting methods do a reasonable job even when the spectra have low signal-to-noise, S/N, ratios. The detection of peaks with small P/B, ratios is much more problemical. Peak identification and fitting procedures may not work well on low intensity peaks particularly in spectra with low S/N ratios. In this study, three procedures for identifying x-ray peaks, with small P/B ratios in spectra with varying S/N ratios were evaluated. The first procedure was the identification of peaks by human analysis. The results from the analysis were then used to set a bench mark for the performance of two computer-based methods in finding small peaks varied widely. In general, the quantitative analysis procedure performed as well as the best human analysts and was better than the qualitative methods.
automated scanning electron microscopy, energy dispersive x-ray analysis, particle analysis, peak identification