SURFACE EFFECTS ON THE 4F HYBRIDIZATION IN CE INTERMETALLICS AS SEEN WITH CE 3D XPS

We present Ce 3d XPS results from Ce7Rh3, CeRh2 and CeRh3 taken with Al K alpha and Mg K alpha X-rays. The Mg-excited spectra are more surface sensitive than those excited by Al K alpha and the differences in the spectral functions are exploited to obtain information on the variation of the 4f configuration in the bulk and at the surface as seen through the multiplet structure in Ce 3d XPS. In strongly hybridized compounds (CeRh2 and CeRh3) the reduction of the hybridization at the surface is well seen while Ce7Rh3 which is weakly hybridized has little, if any, surface effect. In order to quantify the effect we introduce a suitable procedure in data analysis. The ground state properties in the bulk and at the surface are briefly discussed by using the single impurity Anderson Hamiltonian.