Effects of monolayer-substrate dynamical coupling. Argon on graphite

Abstract

The dynamical coupling between a solid monolayer film of argon and a substrate of graphite is examined for its effect upon the inelastic neutron scattering from the combined system. A simple model is used to describe the coupled system and the problem is reduced to a calculation of the vibrational modes of a slab of finite thickness. The results show that there is a significant amount of coupling between the film and the substrate, but that the usual geometry of the neutron scattering experiments for these systems is such that this coupling does not affect the scattering intensity significantly. The result of this calculation is used to justify the background subtraction procedure which is used to determine the dynamical response of the adsorbed film. The importance of the dynamical coupling of the film and the substrate to other aspects of monolayer physics is discussed briefly.