Work function studies of rare-gas/noble metal adsorption systems using a Kelvin probe

Abstract

We present a systematic study of the change in work function of noble metal (111) surfaces (Cu, Ag, Au) when being covered with a monolayer of a rare gas (Ar, Kr, Xe). Using a Kelvin probe the experiments show a decrease of the work function of the adsorbate covered system compared to the clean metal surface, in agreement with physisorption theory. The difference in work function depends both on the substrate and adsorbate being the highest for the $\mathrm{Xe}∕\mathrm{Cu}$ system and the lowest for $\mathrm{Ar}∕\mathrm{Au}$. A comparison is performed with angle-resolved ultraviolet photoemission spectroscopy data using the binding energy shift of the (111) surface states of the same adsorbate/substrate systems, and with density functional calculations on simple model systems.