3p resonance photoionization of the valence band in metallic Ca: Atomic and solid-state many-body effects

The valence-band photoemission of metallic Ca is shown to be resonantly enhanced in the region of 3p excitation. The general shape of the resonance profile can be explained as an atomic phenomenon, namely, a 3p-3d giant dipole resonance driving the valence-electron photoionization process. The metal aspects are revealed by the shape of the resonance, the asymmetry of which reflects the 3d character of the valence band, and by additional structure, which probably represents a coupling to shake-up processes. © 1984 The American Physical Society.