Chemical state analysis employing sub‐natural linewidth resolution PIXE measurements of Kα diagram lines

Abstract A high‐energy resolution crystal spectrometer in Johansson geometry, which allows energy resolution below the natural linewidth of the Kα diagram lines, was employed in the measurements of proton‐induced Kα x‐ray emission spectra of titanium and sulfur pure and compound targets. The results demonstrate a clear dependence of the Kα energy shifts on the chemical state of the element in the sample. This dependence permits the chemical state speciation of low‐ Z elements in an unknown sample by employing high‐resolution PIXE measurements of the Kα line. The potential of the technique in speciation studies is demonstrated in the case of an aerosol sample. The analysis of the Kα line obtained from the high‐energy resolution proton‐induced S Kα x‐ray spectrum allowed the identification of sulfur in the aerosol sample as sulfate ([SO 4 ] 2− ). Copyright © 2005 John Wiley & Sons, Ltd.