Theoretical study on the effect of electron-hole pair excitations in resonant X-ray emission spectroscopy for Ce intermetallic compounds

We calculate Ce 4f --> 3d resonant X-Ray emission spectra (4f --> 3d RXES) of Cc intermetallic compounds on the basis of the impurity Anderson model. The calculation is based on the second-order optical formula and the excitation of electron-hole (e-h) pairs in the conduction band is taken into account. In the calculation of the first-order optical processes such as X-Ray photoemission spectroscopy (XPS) and X-Ray absorption spectroscopy (XAS) for rare earth systems, even if they are metallic ones, the effect of e-h pairs is usually neglected on the basis of the 1/N-f expansion. We will point out the importance of taking into account e-h pairs in RXES by showing the calculated results of 4f --> 3d RXES. In these spectra, the structures originating from e-h pairs newly appear, and the spectral weight transfer from the configuration without e-h pairs to that with e-h pairs is clearly observed. The reason why the effect of e-h pairs clearly appears in RXES is also discussed.