Appearance potential spectroscopy studies with Fe/Ni alloys

Abstract

Soft X-ray appearance potential spectra were recorded for a series of Fe/Ni alloys whose compositions in the surface region were determined by means of Auger electron spectroscopy. The L₃ appearance potentials (correlated with the binding energies of 2p_3/2 electrons) of Ni increase by 0.5 eV between 0 and 30% Fe and then at even higher Fe concentrations remain constant. The corresponding values for Fe are practically unaffected by alloying. This effect is tentatively ascribed to a local intra-atomic reorganization process of the Ni valence electrons. A quantity derived from the intensities of the APS peaks which is correlated with the (local) densities of unfilled states above E_F varies linearly with the alloy composition.