It is shown that the two-peak structure of the $4f$ electron photoemission spectrum of Ce metal and its compounds may arise from two kinds of final states, those with and those without screening by a Ce $5d$ electron in an impurity state. A comparison between theory and experiment reveals that the $\gamma -\alpha$ phase transition is accompanied by a very slight increase in conduction-electron population.

• Received 3 May 1982

DOI:https://doi.org/10.1103/PhysRevB.26.7052