Electronic structure of sulfur studied by X-ray Absorption and Emission Spectroscopy.

An X-ray spectroscopy and theoretical study of the chemical state of several sulfur bearing minerals and a synthetic sodium sulfite sample was performed. X-ray absorption and high-resolution Kr X-ray emission spectra were recorded and compared to ab initio quantum chemical calculations. A consistent interpretation of the chemical shift in the Kr emission spectra is obtained based on three different theoretical approaches (density functional theory, multiple scattering theory, and atomic multiplet theory). An analysis of the theoretical sulfur orbital population and valence bond is in agreement with the fluorescence energy position of the Kr lines even within the sulfide (S2-) series. It is shown that the Kr energy shifts can be used for a quantitative determination of the proportion of different sulfur species in heterogeneous samples