CLASSICAL DYNAMICS SIMULATIONS OF SIME3-SURFACE SCATTERING( ION)

This paper presents classical dynamics simulations of Si(CD3)(3)(+) sc attering from a hexanethiolate self-assembled monolayer on Au(111) and from a clean Au(111) surface. Simulations are performed with a united atom model using purely repulsive scattering potentials. These simula tions predict the partitioning of the incident ion kinetic energy into the scattered ion kinetic energy and the internal modes of both the s urface and the ion. For the organic surface, the simulations predict e nergy transfer to surface, ion internal, and ion kinetic energies of 0 .78, 0.11, and 0.12 of the collision energy. The corresponding transfe r efficiencies of 0.12, 0.21, and 0.65 were calculated for the Au(111) surface. These computational results compare well with the experiment al results on the same systems which are reported in the preceding pap er. The simulations predict near specular scattering for both surfaces . They also demonstrate that the ion penetrates only the topmost two t o three layers of Me atoms of the organic surface and that it spends u p to 250 fs in contact with the surface. Finally, these calculations d etermine the dependence of energy transfer on the incident ion angle. (C) 1997 American Institute of Physics.