Nucleation of pentacene on silicon dioxide at hyperthermal energies

The nucleation of pentacene on silicon dioxide, incident at hyperthermal energies, has been investigated with atomic force microscopy. The incident kinetic energy of the pentacene molecules strongly influences the process of adsorption-the adsorption probability decreases with increasing incident energy, indicative of trapping-mediated adsorption. In addition, the trapping probability of pentacene decreases with more glancing angles of incidence, a result inconsistent with so-called normal energy scaling. Analysis of the dependence of the island density on the growth rate in the submonolayer regime indicates that growth at all energies is consistent with a critical cluster containing four molecules. (c) 2005 American Institute of Physics.