We present a photoemission study of the Ce 4f electron in materials which range from the localized, trivalent (4f1) compounds CeH2 and CeAl2 to the reportedly tetravalent (4f0) compounds CeRh3 and CeRu2. Using synchrotron radiation in the photon energy range of 10h140 eV, we compare the valence-band emission of the Ce compounds with that of the analogous La compounds, paying particular attention to resonant behavior near the 4d4f transition threshold. In addition, we use the partial photoelectron yield as an indicator of the degree of 4f localization as well as occupation. We find no evidence of a change in 4f occupation across the series CeH2.1CeRu2. Instead, we find an increase in the width of the 4f emission and an increase in the effect of the 4f electron on the remaining band states. We conclude that the apparent valence changes in these particular compounds are due primarily to hybridization effects, in agreement with recent band-structure calculations.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics