RESONANT PHOTOEMISSION IN HIGHLY LOCALIZED VERSUS WEAKLY LOCALIZED SOLIDS

We report on comparative study of angle-resolved photoelectron spectra of Ni metal and CeGd at the M(III) and N(IV,V) soft-x-ray absorption threshold, respectively. On M(III) resonance, the valence-band photoem ission (PE) intensity of Ni follows a cos2-behavior, while the intensi ty of the 6-eV satellite is independent of the angle of emission relat ive to the E-vector of the incoming beam. On the other hand, the 4f Ce PE signal behaves is-proportional-to cos2 on N(IV,V) resonance. This clearly shows that the resonant enhancement of the 6-eV PE satellite o f Ni is mainly caused by an incoherent Auger decay and cannot be descr ibed as a resonant PE process.