REPLICATE CORE LEVELS AS A PROBE OF VALENCE-FLUCTUATION MATERIALS

For rare-earth elements having two different 4f configurations in the same material, 3d and 4d core-level photoemission spectra will exhibit two sets of structures, or replicas, each corresponding to one of the 4f configurations. Our estimates of the positions of these structures agree with the available data and suggest the utility of replicate core levels as a useful probe of valence-fluctuation materials. © 1979 The American Physical Society.