Theoretical prediction of S Kβ fine structures in PIXE-induced XRF spectra

Sulfur is one of the most important elements found in air pollutants. A PIXE-induced XRF system equipped with a crystal spectrometer is a candidate to analyze chemical states of S in the pollutants. To aid in the design of the spectrometer for this purpose, fundamental data have been collected by calculating S Kβ spectra by use of the discrete variational Xα (DV-Xα) method for molecular orbital calculations. The calculated spectra have very faithfully reproduced XRF spectra observed for mixtures of Na₂SO₄, Na₂SO₃ and ZnS using a Ge (1 1 1) flat crystal spectrometer, which were used as representative chemical species including SO₄^2- and SO₃^2-, and as an example of sulfides in the air pollutants.