Valence-band resonance in photoemission from Ni(001) and its relation to the 6-eV satellite

Abstract
A pronounced final-state dependence of interband transitions near the X point of the Brillouin zone is observed in photoemission spectra of Ni(001). In accord with earlier theoretical suggestions the ‘‘resonancelike behavior’’ of these transitions occurs in the same spectral range as the widely studied resonant 6-eV satellite in Ni, i.e., near 65-eV photon energy. A detailed theoretical and experimental analysis shows, however, that this coincidence is fortuitous and that different mechanisms are operable. The polar angular dependence of the resonant 6-eV satellite is investigated by means of angle-resolved constant-initial-state spectroscopy, and it is argued that part of the observed behavior can be understood as an interference effect.