Conventional
gas surface interaction (GSI) models and molecular
dynamics (MD) simulations have been compared with angular distributions
and average translational energies for N2 scattered from
highly oriented pyrolytic graphite (HOPG) measured by angle and velocity
resolved molecular beam scattering experiments. The translational
energy and angular distributions of the scattered N2 were
obtained for incidence energies near 30 and 68 kJ mol–1, incidence angles of 30°, 45°, and 70°, and a surface
temperature of 677 K. The trajectories of scattered nitrogen molecules
were found to fall into three main categories, i.e., single collision,
multiple collisions with escape, and multiple collisions without escape.
While the conventional GSI models did not match the translational
energy and angular distributions obtained from the experiments, the
results obtained from MD simulations were found to be in good agreement.
The MD simulations also showed that the number of surface layers used
to model the HOPG surface and the carbon–nitrogen Lennard-Jones
potential are important in improving the agreement between the simulations
and the experiments.