Theoretical Study on the Effect of Electron–Hole Pair Excitations in Resonant X-Ray Emission Spectroscopy for Ce Intermetallic Compounds

We calculate Ce 4 f →3 d resonant X-Ray emission spectra (4 f →3 d RXES) of Ce 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 4 f →3 d 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.