X-RAY L(2,3) RESONANT RAMAN-SCATTERING FROM NIO - SPIN-FLIP AND INTERMEDIATE-STATE RELAXATION

We present measurements of x-ray resonant Raman scattering from NiO wi th L-2,L-3 excitation and calculations in an ionic model based on the process (2)3d(8))-->(2p(5)3s(2)3d(9))-->(2p(6)3s(1)3d(9)). The agreeme nt between theory and experiment is good from below threshold up to 2. 5-3 eV above threshold. By comparing theory and experiment, we show th e effect of crystal-held splitting and the contribution bringing the N i2+ triplet ground state to a singlet final state with excitation abov e the L-3 edge. When the excitation energy exceeds the L-3 threshold b y about 3 eV, we present evidence that the intermediate state,in the s cattering can also relax to a state similar to that created with thres hold excitation. We suggest d-d excitation and electron-hole pair exci tation as the origin of this relaxation.