Energy distribution curves from La and Pr were taken from 32 to 80 eV photon energies. Above 50 eV the valence-band photoemission in La is very weak, implying that previous studies of Ce have underemphasized the $4f$ contributions. Pr exhibits two peaks attributable to $4f$ electrons, similar to the structures in Ce.

• Received 17 January 1984

DOI:https://doi.org/10.1103/PhysRevLett.52.2180