Relation between X-Ray-Raman and Soft-X-Ray-Absorption Spectra

A spectrum of x-ray inelastic scattering of copper $K{\alpha }_{1}K{\alpha }_2$ radiation scattered by metallic lithium through $k=6.87\mathrm{}\times {10}^{10}$ was obtained. (These conditions correspond to a momentum transfer $2\theta =115\mathrm{}°$ ${\mathrm{m}}^{-1\mathrm{}}$.) The spectrum is compared quantitatively to an experimental soft-x-ray-absorption spectrum of lithium. This comparison serves as an experimental verification of the relation between x-ray-Raman spectra and soft-x-ray-absorption spectra. The method renders possible the study of solid-state effects via x-ray Compton-Raman experiments without ad hoc assumptions concerning the wave functions of the inner electrons. Also presented is some evidence of the failure of a random-phase approximation and the impulse approximation in the region under investigation.