Auger effect in high-resolution Ce3d−edgeresonant photoemission

Abstract

The bulk-sensitive Ce $4f$ spectral weights of various Ce compounds including ${\mathrm{CeFe}}_{2},$ ${\mathrm{CeNi}}_{2},$ and ${\mathrm{CeSi}}_{2}$ were obtained with the resonant photoemission technique at the Ce $3d$ edge. We found that the line shapes change significantly with the small change of the incident photon energy. Detailed analysis showed that this phenomenon results primarily from the Auger transition between different multiplet states of the Ce $\underset{\ifmmode\bar\else\textasciimacron\fi{}}{{3d}_{5/2}}{4f}^{2}$ (bar denotes a hole) electronic configuration in the intermediate state of the resonant process. This tells us that extra care should be taken for the choice of the resonant photon energy when extracting Ce $4f$ spectral weights from the Ce $3d\ensuremath{-}\mathrm{e}\mathrm{d}\mathrm{g}\mathrm{e}$ resonant photoemission spectra. The absorption energy corresponding to the lowest multiplet structure of the Ce $\underset{\ifmmode\bar\else\textasciimacron\fi{}}{{3d}_{5/2}}{4f}^{2}$ configuration seems to be the logical choice to obtain genuine Ce $4f$ spectral weight from the Ce $3d$ resonant photoemission data.