X-ray emission from chemically bound atoms

Abstract

For the application of PIXE and related X-ray spectroscopic techniques to inferring ionization cross sections or elemental abundances from measured X-ray line intensities, precise knowledge of de-excitation parameters such as fluorescence yields and relative X-ray line intensities is indispensable. For a theoretical derivation of such quantities due consideration must be given to both intra- and interatomic relaxation which have different effects on radiative one-electron and nonradiative two-electron transitions. In particular, the scattered-wave approach to the electronic structure has proved exceedingly useful to simultaneously model X-ray and Auger transitions occurring in atoms embedded in their actual surroundings, thereby including the effects of both ordinary static as well as configuration-induced transitory covalency. Recent studies of environmental effects on S K-shell Auger satellite spectra disclosed some implications for X-ray spectroscopic measurements. Particular emphasis is laid on the relationship to the speciation of third-row atoms in samples of practical relevance.