New-Type Components of the X-Ray Scattering Cross Section in Matter

New spin-dependent components of the cross sections for nonresonant and resonant X-ray scattering by atoms of matter have been found using quasi-relativistic expansion of the Dirac Hamiltonian in the Foldy–Wouthuysen representation. Spin-dependent components of resonant scattering, which are maximum at the K-absorption edge in magnetic materials, contain information about the spin density of p states in the continuous spectrum of material atoms.