X-Ray Absorption Near Edge Structure in Metals: Relativistic Effects and Core-Hole Screening

A long standing theoretical problem “the absence of a white line in the $L_2$ x-ray absorption near edge spectrum of Pt metal” has been solved taking into account relativistic effects and the presence of a core hole. The photoabsorbing atom is treated as a single-site impurity in our theory of x-ray absorption near edge structure (XANES) based on the fully relativistic layer Korringa-Kohn-Rostoker Green-function method. Comparing the XANES of Al with those of Cu and Pt, it is found that for transition metals $d$ electrons play a dominant role in deep core-hole screening, whereas in Al $\mathrm{sp}$ electrons are important.