3D-]4F RESONANT PHOTOEMISSION IN RARE-EARTH SYSTEMS

3d → 4f resonant photoemission (PE) data are presented for Sm and Gd metal as well as for the intermetallic compounds CeAl2, EuPd3, TmAl2, and YbAl2. The observed effects are generally similar as in the corresponding 4d → 4f resonances, they are, however, considerably different in magnitude. For Tm3+ and Yb3+, enhancement factors of 40 and 48, respectively, are derived for the 4f PE cross-section. In case of Gd3+, quintet states are observed that resonate at the M5 threshold through a separate spin-flip channel. Differences between constant-initial-state and total-electron-yield spectra of Tm, Eu, and Sm reveal that resonant decay channels involving 4f electrons are blocked at certain excitation energies. © 1990 IOP Publishing Ltd.