ESCA studies of some mixed-valence rare-earth intermetallics

ESCA (or XPS) studies of some rare-earth intermetallics were carried out using ESCA (3) Mark II and 'ESCALAB' machines from V G Scientific. The mixed valence nature of EuCu2Si2 and EuNi2P2 intermetallic compounds has been established. The 3d core-level photoemission spectra of Eu in EuCu2Si2 and EuNi2P2 exhibit two sets of structures corresponding to two different valence states of the rare-earth ions. Each of these sets shows simple spin-orbit splitting. The replicate splitting measured by us agrees well with those calculated by Herbst and Wilkins. The 3d core-level photoemission spectra of Eu is free from the multiplet splitting and satellite structure. The importance of 3d core-level photoemission studies in the understanding of valence fluctuation phenomenon has been emphasized