Molecular diffusion in monolayer and submonolayer nitrogen

The orientational and translational motions in a monolayer fluid of physisorbed molecular nitrogen are treated using molecular dynamics simulations. Dynamical response functions and several approximations to the coefficient of translational diffusion are determined for adsorption on the basal plane surface of graphite and on a fictitious uncorrugated graphite surface. The rotational diffusion constants in the plastic crystal and in the fluid phase are calculated. The possibility of observing these phenomena with quasielastic scattering experiments is discussed. The wave vector range is determined where the ballistic approximation to the translational molecular self-correlation function is accurate.