RAMAN, NON-RAMAN, AND ANTI-RAMAN DISPERSION IN RESONANT X-RAY-SCATTERING SPECTRA OF MOLECULES

The character of Raman dispersion is investigated for radiative and no nradiative resonant x-ray scattering of systems with vibrational degre es of freedom. It is shown that the center of gravity of the resonantl y scattered x-rays and electrons of such systems is strongly dependent on frequency and spectral shape of the incoming x-ray radiation and o n the parameters defining the potential surfaces of the states involve d in the scattering event. Contrary to nonresonant x-ray and Auger emi ssion, narrow band resonant excitation leads to a strong nonlinear dep endence of the center of gravity, with an asymmetrical frequency depen dence for this quantity. Contrary to atomic systems it is shown that r esonant x-ray scattering of molecules often is guided by an anti-Raman dispersion law.