Generation of 3D hydrocarbon thin films via organic molecular cluster collisions

Thin film growth through the consecutive impact of energetic ethyne molecular clusters with a non-rigid, hydrogen-terminated diamond (111) surface in vacuum has been studied using molecular dynamics simulations. A second-generation version of the reactive empirical bond-order potential for hydrocarbons developed by Brenner, that has been modified to include long-range van der Waals interactions, is used in the simulations. The velocities considered are in the hyperthermal region and are comparable with those that can trigger shock-induced chemistry in energetic materials. The resulting film structure is predicted to be significantly different from diamond, graphite, or diamond-like amorphous-carbon thin films. The evolving film morphology is discussed in detail and the results compared with single cluster impacts involving a comparable number of molecules.