Theory of core-level inelastic X-ray scattering spectra and partial local densities of states in low-Z atom crystals

Abstract

A method for calculating the double-differential cross sections of the inelastic X-ray scattering (IXS) associated with low-Z-atom-K-level excitation of solids is proposed. We have included both the first- and the second-order contributions of one-electron perturbation theory. The second-order contribution is shown to be significant only for comparatively small initial photon energy (h(cross) omega 0<2 keV). The first-order term is proved to be determined by p partial local densities of electron states (p LDOS) whereas the second-order term is determined by s LDOS. An expression is proposed which enables us to determine the p and s LDOS from experimental IXS spectra measured for different initial photon energies and transferred momenta. Using available experimental IXS spectra and X-ray absorption spectra we have determined the pi * and sigma * p LDOS for graphite crystal. The results obtained are compared with the theoretical pi * and sigma * LDOS calculated using the full multiple-scattering method. The calculated and experimental LDOS are in reasonable agreement, both as regards peak positions and absolute values.