Investigation of the electronic structure in Cu-Au I using x-ray-photoelectron spectroscopy

We report x-ray-photoemission measurements on Cu-Au I and show that details of the valence-band spectrum are in agreement with recently published band-structure calculations. We find that upon alloying, the binding energy of the Au 4f core level increases by 0.30±0.05 eV and that of the Cu 2${\mathit{p}}_{3/2}$ core level decreases by 0.27±0.05 eV. We suggest that the tetragonal distortion is related to increased ionicity in the Cu-Au bonds. Characterization studies indicate that Au segregates to the surface of a polycrystalline sample.