Decomposition of wavelength dispersive x-ray spectra

Abstract

Line shapes of atomic lines and soft x-ray emission bands measured with a wavelength dispersive spectrometer (WDS) with the Electron Probe Micro Analyzer (EPMA) are reviewed. Least square fitting to pseudo-Voigt profiles of the digitally measured spectra are used to account for the presence of non-diagram features (high and low energy satellites) and instrumental induced distortions. The effect of line width and relative intensities on the quality of fits is illustrated. Spectral distortions resulting from the presence of absorption edges within the analyzed wavelength region are illustrated for the case of FeLα,β emission bands for pure Fe and iron oxides. For quantitative analysis, an analytical approach is presented where the measured soft x-ray emission bands are corrected for self absorption before extracting the intensities from the experimental data.

Electron probe microanalysis of Ni-silicides at low voltage: difficulties and possibilities

“…Absorption spectra were obtained from the ratio of two normalized X-ray emission spectra measured at low and high incident electron energy [22][23][24]. As shown by e.g., Chopra [24], absorption spectra obtained in this way are equivalent to X-ray absorption measurements using X-ray beams and thin foil absorbers.…”

Analysis of the K Satellite Lines in X-Ray Emission Spectra

“…According to the selection rules, these transitions are not radiative and the excess of energy L 1 -L 2 or L 1 -L 3 is dissipated by the emission of an Auger electron from the M or N levels. The transition rate of non-radiative Coster-Kronig transitions f ij , where i and j are two subshells within the same energy level, is not permitted for all elements (Rémond, 2002). The double excitation threshold is the value of energy needed to cause double vacancies in the atoms, so the probability to observe satellite lines K is zero for incident energies below this value.…”

“…The vacancy 3p -1 is generated by transitions 3p → 1s that give rise to the line K 1,3  In contrast, the satellite line K'' of the transition metals have a similar origin to the K' in elements of the third period. Several other theories are available to describe the K' low energy feature associated with the K 1,3 emission resulting from transitions involving the partially filled 3d shells of transition elements and their oxides (Rémond, 2002). The Radiative Auger Effect (RAE) produces a broad structure at a lower energy than the characteristic diagram line.…”

Fast and accurate expression for the Voigt function. Application to the determination of uranium M linewidths

“…Although the pseudo-Voigt function has largely been used as an approximated expression to depict the characteristic line profiles [1,2], it may lead to discrepancies too large in some cases. Fig.…”

“…Due to the lack of a closed-form expression for the Voigt function, the pseudo-Voigt function is a usual approach in X-ray spectroscopy [1][2][3][4]. This function is a linear combination of a Gaussian and a Lorentzian.…”