The Theory of the Fine Structure of the X-ray Absorption Spectrum

Abstract

In the interpretation of the fine structure of the X-ray absorption spectrum in solids, the life time of the state of the electron ejected by absorption of a photon is considered. The life time is mainly determined by the inelastic collision cross section between the ejected electron and the atoms in the crystal. With the assumption that the inelastic cross section has a magnitude of the order of one square Angstrom, Kronig's method for the molecule is applied to the solid in order to obtain the variation of the transition probability. The wave function of the final state of the transition is obtained as the sum of the plane wave, whose amplitude decreases with increasing distance from the absorbing atom, and the waves scattered by the neighboring atoms. The calculated results for the K -absorption spectra of copper, nickel and iron agree well with experiments.