Deconvolution in EDS Analysis
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For EDS analysis, it is necessary to highlight that except for the random errors from counting statistics, some factors, however, will contribute systematic errors. Those factors are mainly:
         i) Accuracy of the chemical composition of the standard (if calibration or correction of kAB factors is applied).
         ii) Presence of spurious X-rays.
         iii) Inaccuracy of evaluation of the specimen thickness.
         iv) Inaccurate deconvolution of overlapping peaks.
         v) Inaccurate background-fitting.

Deconvolution can only be done by optimizing the whole line series. However, deconvolution is not necessary if there is no line overlaps in the spectrum.

The deconvolution in EDS analysis can be tricky mainly because:
         i) The shape of the background in the relevant energy range is difficult to model.
         ii) The peak shape is usually not purely Gaussian, making deconvolution difficult.

Figure 2359a shows two schematic spectra obtained from two EDS detectors with energy resolutions at Mn Kα 120 eV and 130 eV, respectively. It is clear that higher spectrum peak can be obtained with better resolution. Consequently, the higher peak improves the peak-to-background ratio and facilitates the spectrum deconvolution.

Schematic spectra obtained from two EDS detectors with energy resolutions at Mn Kα 120 eV and 130 eV, respectively

Figure 2359a. Schematic spectra obtained from two EDS detectors with energy resolutions at Mn Kα 120 eV and 130 eV, respectively.

Figure 2359b shows the deconvolution of an EDX spectrum with peak overlaps, taken from a material that contains O, Ti, N, and C elements.

Deconvolution of an EDX spectrum with peak overlaps

Figure 2359b. Deconvolution of an EDX spectrum with peak overlaps. [1]

[1] J. Berlin, T. Salge, M. Falke, and D. Goran, Recent Advances in EDS and EBSD Technology: Revolutionizing the Chemical Analysis of Chondritic Meteorites at the Micro- and Nanometer Scale, 42nd Lunar and Planetary Science Conference, 2723, (2011).

 

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