Electronic structure of silver overlayers on W(100)

The electronic structure of silver adsorbed on the (100) facet of a tungsten field emitter in the range of coverage from zero to three monolayers has been studied experimentally by means of field and photofield emission spectroscopy. An analysis of work function and total emission current data yields evidence that adsorbed silver reduces the surface density of states at the Fermi energy It is found that adsorbed silver both suppresses the Swanson hump in the surface density of states of clean W(100) and also induces additional structures that depend largely on the number of complete overlayers. The experimental observations are interpreted by means of self-consistent fully relativistic supercell calculations of the layer densities of electronic states at the tungsten-vacuum and at the tungsten-silver-vacuum interface. The calculations predict silver-induced features in the surface density of states that are generally consistent with the experimental observations.