Adsorption of xenon on group VIII and ib metals studied by photoelectric work function measurements

Abstract

The heat of adsorption of Xe and the change in work function by Xe adsorption have been investigated on Cu, Au, Ni, Pt and Rh films using the photoelectron emission technique. The surface potential of Xe appears to be directly related to the heat of adsorption: a large heat of adsorption is accompanied by a large surface potential. These results are discussed on the basis of various models for physical adsorption of inert gases on metals. The heats of adsorption found experimentally can satisfactorily be correlated with the measured surface potentials upon considering the interaction between Xe and the transition metal as charge transfer-no bond interaction. An alternative explanation for the large decrease in work function by Xe adsorption, the classical polarization model, can be rejected since it is unable to explain the high heats of adsorption on group VIII metals and if fails to describe the observed interdependence of the heat of adsorption and the surface potential. These conclusions are in agreement with earlier results obtained by studying the adsorption of Xe on several well defined cyrstal faces of Pt and Ir by field emission microscopy.