X-RAY RESONANT RAMAN-SCATTERING IN THE RARE-EARTHS

This paper develops a theory of resonant Raman scattering within the f ramework of a localized model. Expressions for the scattering amplitud e and cross section are derived by employing the methods of spherical- tensor analysis. a simple factorization is obtained for the geometrica l (angular dependence) and electronic (matrix element) components, whi ch can therefore be studied independently. Photon polarization effects are examined. It is shown that, for fast collisions, the integrated i ntensity is expressible by way of spin and orbital effective operators , thus allowing for a simple interpretation of the scattering process. For the 2p-->4f, 3d-->2p resonance in Gd3+, Dy3+, Ho3+ and Er3+, nume rical calculations of the cross section are discussed. In the case gad olinium, the agreement between calculations and experiments provides f urther evidence for the quadrupolar nature of certain spectral feature s.