X-ray Raman scattering involving electronic continuum resonances

Theory of resonant x-ray elastic and inelastic scattering involving electronic continuum resonances is presented. As for excitation to discrete states the resonant x-ray spectral shape is found to depend strongly on the frequency of incoming photons and on the scattering angle. Contrary to excitation to discrete states, the energy scale of this dependence is defined by the finite delay time of the core-excited electron. It is shown that also the partial absorption cross sections for a continuum resonance can be obtained when the x-ray absorption spectrum is measured in the resonant inelastic x-ray scattering mode. The connection between frequency and angular dependences and the symmetries of the continuum and discrete states involved in the x-ray scattering is derived. The limiting factors for the spectral function under different circumstances are given.