A UNIFYING SCHEME OF INTERPRETATION OF X-RAY ABSORPTION SPECTRA BASED ON THE MULTIPLE SCATTERING THEORY

Abstract

The various schemes for calculating inner shells X-ray absorption spectra are reviewed and shown to be mutually equivalent. The unifying framework is provided by the multiple scattering (MS) theory. In particular the formulation based on the Green's function approach allows one under certain conditions to write the absorption coefficient as a sum of an infinite number of terms which have a direct physical meaning. The conditions under which this expansion is possible is discussed and as a consequence a unifying scheme of interpretation of X-ray absorption spectra is proposed. Finally an approximate formula for the rapid evaluation of the n-th order term of the expansion is given