Theory of Off-Resonant p·A Scattering of X-Rays in Solids

Abstract

Inelastic scattering of X-rays by an inner-shell electron in solids is treated theoretically under the condition of 2πa⁄λ₀<1 and 10I\gtrsimhν₀\gtrsimI, where λ₀ and hν₀ are a wavelength and an energy of the incident X-rays and a and I are the radius and the ionization energy of the inner-shell electron, respectively. In this case, the contribution by the p·A-term in the Hamiltonian is not negligible compared to that by the A²-term, but gives an appreciable p·A band in the scattering spectrum. As an example, the scattering of soft X-rays by K-electrons in lithium is treated. The result shows the cross-over of the spectral intensity from the A²-term dominant Raman band to the p·A-term dominant band as hν₀ becomes smaller. An experiment using the monochromatic bright radiation from an undulator equipped in a synchrotron orbit would be useful to confirm the present theory.