Photoemission study of desorption of monolayer argon from Au(111) surface

We present a photoemission study of desorption of a monolayer of argon (Ar) physisorbed on the Au(111) surface by monitoring the Ar 3p core-level spectral intensity and shape as a function of temperature. The variation of the Ar 3p signal indicates a difference of 7 K between the start and finish of the desorption process, the desorption temperature being 46 K. From an analysis of the Ar 3p core-level line shape, we have related this to two types of hybridization of the Ar atoms with different regions of the herringbone reconstructed Au(111) surface. The interaction between the ArA and Au atoms in the discommensurate region is relatively weaker compared to that between the ArB and Au atoms in the fcc and hcp regions of the herringbone reconstructed surface resulting in the desorption of the former at a lower temperature (41 K).