X-RAY RAMAN-SCATTERING INVOLVING ELECTRONIC CONTINUUM RESONANCES

Theory of resonant x-ray elastic and inelastic scattering involving el ectronic continuum resonances is presented. As for excitation to discr ete states the resonant x-ray spectral shape is found to depend strong ly on the frequency of incoming photons and on the scattering angle. C ontrary to excitation to discrete states, the energy scale of this dep endence is defined by the finite delay time of the core-excited electr on. 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 conn ection 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 differe nt circumstances are given.