Determination of Elemental Intensities from Direct Auger Spectra by Pre-Filtered Least Squares Fitting

摘要

The measurement of Auger peak intensities in the direct energy spectrum is made difficult by the presence of a high curving background and peak overlaps. A procedure developed for the analysis of energy-dispersive X-ray data is applied to this problem; spectra are cross-correlated with a digital frequency filter to suppress the continuum, prior to a linear least squaraes fitting of elemental reference spectra to an unknown Auger spectrum. The major advantages of this approach to quantification are that it does not require an explicit model for the background shape nor the selection of points away from peaks suitable for background fitting. Experimental studies show that the filter-fit technique provides an acceptably accurate quantification of overlapped Auger peaks. In addition, the fit is relatively insensitive to spectrum shape modifications introduced by altering experimental parameters such as excitation voltage, analyzer resolution and sample topography. The filter-fit gives more reproducible results for noisy spectra than the application of sensitivity factors to differential spectra calculated from the same raw data.