X-ray M-4,M-5 resonant Raman scattering from La metal with a final 4p hole: Calculations with 4p-4d-4f configuration interaction in the final state and comparison to experiments - art. no. 235113

We consider the x-ray resonant Raman scattering (RRS) in La in the whole M- 4,M-5 region ending with a state with a 4p hole, along the sequence 3d(10)4 f(0)-->3d(9)4f(1) --> 3d(10)4p(5)4f(1). The final state configuration mixes with that with two 4d holes, i.e,, 3d(10)4d(8)4f(n+2) having almost the sa me energy. Thus RRS must be described by introducing final-state configurat ion interaction (CI) between states with one 4p hole and with two 4d holes, This approach allows detailed experimental data on La metal to be interpre ted on the basis of a purely ionic approach. It is shown that the inclusion of CI is crucial and has very clear effects. The calculations with the Kra mers-Heisenberg formula describe all measured spectral features appearing i n the strict Raman regime, i.e., dispersing with the incident photon energy . In the experiment also a nondispersive component is present when the exci tation energy is greater than about 2 eV above the M-5 peak. The shape and position of this component is well accounted for by a model based on all po ssible partitions of the excitation energy between localized and extended s tates. However the intensity of the nondispersive component is greater in t he measurements, suggesting a rearrangement in the intermediate excited sta te. The comparison of ionic calculations with the metal measurements is leg itimate, as shown by the comparison between the measurements on La metal an d on LaF3 with M-5 excitation giving the same spectrum within the experimen tal accuracy. Moreover the experiment shows that the final lifetime broaden ing is much greater in the final states corresponding to lower outgoing pho ton energies than in the states corresponding to higher outgoing photon ene rgies.