Comparison of amorphous and liquid alloys by photoelectron spectroscopy

Photoemission data of liquid AuSn alloys are presented and compared with corresponding measurements on amorphous vapour-quenched films. A fairly close general similarity between the valence bands of the two phases is observed. This result supports earlier studies of the atomic structure of the amorphous films which have been interpreted in terms of a liquid-like structure with a strong tendency to compound formation within the nearest-neighbour arrangements. Distinct deviations of spectra measured on the liquid samples compared with the amorphous phase have been observed; the Au 5d band is shifted to lower binding energies and no density-of-states minimum is observed at E_F. The Au d band exhibits a continuous temperature-dependent shift in the liquid state which has been observed for the first time and which can be extrapolated to −193 °C in the amorphous phase. The origin of this temperature effect is discussed in terms of changes in the electron density and structural alterations in the short-range order at the gold site.