Alloy formation of ultrathin indium and silver layers on W(1Â 1Â 0): A photoemission study

We have studied the intermixing of ultrathin indium and silver layers deposited sequentially on W(1 1 0). The process of alloying was monitored via angle-resolved ultraviolet photoemission from valence states and the In4d level, and photoelectron spectroscopy of Ag and In core-levels using monochromatized AlKα radiation. Alloying starts effectively at room temperature and is completed after a short anneal at 600 K. While Ag4d valence state data indicate complete intermixing, quantitatively almost identical to alloying in AgxIn1−x bulk alloys, no charge transfer to In could be detected: the In4d binding energies are identical to those observed for clean In deposited on W(1 1 0). The process of alloying appears to be purely geometrical (as reflected in photoemission) and no significant difference between 2D layered alloys (even in submonolayer quantities) and 3D bulk alloys could be identified.