Potts, P. J. and Tindle, A. G.
Evaluation of spectrum overlap correction in energy-dispersive x-ray spectrometry using the digital filter deconvolution procedure: Application to selected interferences encountered in the microprobe analysis of minerals.
X-ray Spectrometry, 20(3)
An evaluation was undertaken to characterize the accuracy and effectiveness in the deconvolution of energydispersive x-ray spectra of the overlap correction procedure based on a digital top hat filter and least-squares fitting of library spectra using an algorithm developed by Statham. This deconvolution procedure was applied to x-ray spectra recorded by electron microprobe to represent interferences that range in severity from minor to severe, specifically overlap between (i) Cr/Mn K lines, (ii) Ba L and Ti K lines, (iii) Au/Pt L and M lines and (iv) Bi/Pb L and M together with S K lines. A novel calibration procedure was used to simulate spectra and so avoid the requirement to obtain and analyse a large number of mineral standards. This procedure involved superimposing x-ray spectra from individual elemental standards counted for a range of count times suitable for testing the deconvolution program. The results demonstrated that reliable deconvolution could be achieved down to <1% Cr in a manganese matrix, 2.5% Ba in a titanium matrix, <2.5% Au in a platinum matrix (based on either L or M lines) and about 2.5% Bi in a Bi-Pb-S matrix using the M lines of Bi and Pb. Within the fitting error calculated by the deconvolution program, bias from expected values was not detected excepted when Bi, Pb and S were fitted to the simulated spectrum of bismuthite (Bi2S3). Small discrepancies in the Bi and S values were then observed. Overall, it was concluded that in cases of severe overlap, numeric data from the spectrum deconvolution program were a more reliable indicator of the presence of an element than visual examination of the original spectrum.
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