The shape of Lα X-ray peaks analyzed by means of a LiF (200 plane) monochromator was described by a pseudo-Voigt function:
P(λ) = 0.35 P1(λ)+ 0.65 P2(λ)
where P1(λ) and P2(λ) are a Gaussian and a Lorentzian distribution centered at the same wavelength, with the same amplitude and half-width and in relative proportion 0.35 and 0.65 respectively. For peaks occurring at wavelength greater than ≃ 0.17 nm, a Gaussian offset was added in order to correct the asymmetry of peaks resulting from the monochromator mounting within the spectrometer.
The effective wavelength resolution was obtained by quadrature addition of the instrumental resolution and the natural width of the X-ray peaks. It has been shown that the difference in peak width of the L emission peaks of the lanthanide elements resulted from their difference in their natural widths. For these elements, the Lβ2, Lγ1 and Lγ2 were found to be accompanied by non-diagram lines, Lβ14, Lγ9 and Lγ10 respectively. The wavelength separation distances Lβ14-Lβ2, Lγ9-Lγ1 and Lγ10-Lγ2 were found consistent with the distances derived from the plasmon theory.
Remond, G.; Coutures, Ph.; Gilles, C.; and Massiot, D.
"Analytical Description of X-Ray Peaks: Application to L X-Ray Spectra Processing of Lanthanide Elements by Means of the Electron Probe Micro-Analyzer,"
Scanning Microscopy: Vol. 3
, Article 9.
Available at: https://digitalcommons.usu.edu/microscopy/vol3/iss4/9