RESONANCE AND ANTIRESONANCE IN INVERSE-PHOTOEMISSION - DISCRIMINATINGLOCALIZED AND EXTENDED STATES IN CERIUM SYSTEMS

The electron addition spectrum of the intermediate-valence material Ce Rh3 exhibits a dramatic dependence on the excitation energy near the C eM(5) (3d --> 4f) absorption edge. The cerium 4f spectral intensity is first strongly depressed, and then resonantly enhanced with respect t o the band contribution, with an overall cross-section variation of al most three orders of magnitude. These results show that, in close anal ogy with resonant photoemission, a comparison of on- and off-resonance spectra can be used to identify and separate the signal from the loca lized and the extended electronic states in Ce systems.