Binding energies and work-function changes in Eu/sub x/La/sub 1en-dashx/Al2 compounds studied by x-ray photoelectron spectroscopy

The intermetallic compound Eu/sub x/La/sub 1en-dashx/Al2 has been studied by x-ray photoelectron spectroscopy with Al Kα radiation at concentrations x=0, 0.03, 0.1, and 1. The dependence of the Eu-4f line shape on the partial density of states at the Fermi energy is discussed. The Eu-4f excitation energy in the compounds was found to be Δ/sub -/=1.0 +- 0.1 eV independent of the Eu concentration. This is 0.9 eV smaller than the value reported for metallic Eu. The energy shift is mainly due to Fermi-energy changes as confirmed by work-function measurements of the samples. The resultant shift is discussed in terms of charge transfer together with existing Moessbauer-isomer-shift data