Electron-spectroscopic studies of theCuxPd1−xalloy system: Chemical-shift effects and valence-electron spectra

The valence- and core-electron spectra have been investigated for a series of ${\mathrm{Cu}}_x{\mathrm{Pd}}_{1-x}$ alloys by means of ESCA (electron spectroscopy for chemical analysis). In the dilute limits a subtraction method is applied to derive the contribution of the low-concentration components to the valence-electron spectra. The Pd core-line asymmetry scales with the local palladium density of states at the Fermi level, and it is heavily reduced in the dilute palladium limit. For the Pd $M_{45}{N}_{45}{N}_{45}$ Auger spectrum a bandlike contribution is identified in addition to the dominating quasiatomic part. Special attention is paid to the chemical shifts of the Pd and Cu core levels as a function of alloy concentration. From these and the two-hole Auger final-state energy shifts various thermochemical data are derived and compared with experiment. In general, a good agreement is obtained, suggesting that ESCA calorimetry might become a very rapid and useful method for thermochemical investigations.