Resonant photoemission experiments at the 4d threshold have been carried ou
t in ultra-thin films of cerium deposited on monocrystalline Fe and Pd. In
the Ce/Fe system, we have unambiguously demonstrated the reduced Ce configu
ration admixture in the surface layer by evaporating one monolayer of an ap
propriate element to suppress the surface contribution. In the Ce/Pd system
, the spectra clearly show an exceptional configuration mixture suggesting
an intermediate valence regime but they cannot be described in the single i
mpurity Anderson model. (C) 1999 Elsevier Science B.V. All rights reserved.