SURFACE AND INTERFACE CERIUM ELECTRONIC CONFIGURATION IN CE FE (100)/

The cerium electronic configuration of very thin films deposited on Fe (100) has been studied by core level photoemission. In the low-coverag e regime (less than or equal to 1 monolayer), cerium atoms are in a tr ivalent state (4f(1) configuration). For larger coverages, cerium atom s exhibit a mixed valent state. This behaviour reflects the valence ch ange of covered cerium atoms at the interface and results from the inc rease in the hybridization strength for these interface atoms. Owing t o an original method, we were able to directly decompose our experimen tal spectra in two contributions corresponding to the covered (''bulk' ') and non-covered (surface) atoms.