In this work, we present the way we perform high-resolution wavelength-dispersive X-ray spectrometry in the ultra-soft X-ray range. For this purpose, we use a reflection zone plate spectrometer working, as a variable line spacing grating spectrometer, in the 40 - 110 eV spectral range. We show that the shape of the emission bands can be reproduced by simulation of spectra obtained from the local and partial density of states calculated with the density functional theory. The knowledge of the electronic structure of the material under consideration is important to properly interpret the spectra, which can be complicated when many elements are present in the sample, such as the amblygonite phosphate. We also show the first attempt of elemental quantification of an AlCuLi alloy from intensities measured with the reflection zone plate spectrometer. The obtained mass fractions are in good agreement with those obtained in a standard way from measurements performed in the soft X-ray range with crystal spectrometers.
Philippe Jonnard (Thu,) studied this question.