Effects on the structure of monolayer and submonolayer fluid nitrogen films by the corrugation in the holding potential of nitrogen molecules

Molecular dynamics simulations have been used to study the effects of the c orrugation in the holding potential of nitrogen molecules on the structure of fluid monolayer and submonolayer films of the molecules on a solid subst rate. Structures of monolayer and submonolayer fluid films of nitrogen mole cules adsorbed on graphite and on a model uncorrugated "smooth" graphite su rface are compared. For films on the "smooth" graphite surface the melting temperature is lowered by 7 K. Contrary to what is found for films on the c orrugated surface, the simulations show that there is a region of liquid-ga s coexistence, demonstrating that this is a normal triple point system. A d iscrepancy between calculated and experimental melting temperatures of subm onolayer films was traced to the intermolecular potentials. These have been tested by comparing molecular dynamics simulations of isosteric heats of a dsorption in fluid films with experimental measurements. The establishment of the effects of the corrugation in the holding potential on the structure provides a basis for the study of the effects on the dynamical excitations in the films. (C) 2001 American Institute of Physics.