Roles of Dynamical Screening by the 5dand 4f-Electrons in the Optical Excitation Spectra of Ce-Pnictides

The core-level and the 4 f -valence electron photoemission spectra of CeSb are analyzed considering the screening by both the 5 d and the 4 f -electron. The calculation is done based on the cluster model. The screening by the 5 d -electron leads to the energy dependent reduction of the mixing value between the 4 f and the band-electrons. As a direct evidence of the dynamical screening by the 5 d -electron, a satellite is expected at about 10 eV higher binding energy than the main peak with about a half of intensity for the main peak. This satellite corresponds to the p - d anti-bonding state and explains the peak seen in the experiment which has been attributed to the plasmon side band. Similar satellite is expected also in the core-level XPS of the Sb site.