Pushing the limits of classical modeling of bombardment events in solids

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Abstract
Bombardment of solids with keV atoms leads to violent collisions with subsequent ejection of target particles. This review discusses how classical molecular dynamics simulations designed to describe the bombardment events can give insight into microscopic processes where not only classical but also quantum effects such as electronic excitation and organic reactions play an important role. By incorporating a simple excitation/de-excitation model into the simulation, we have shown that collisional events are important to describe the distribution of excited state atoms measured experimentally. Molecular dynamics simulations employing a reactive many-body potential of small hydrocarbon molecules adsorbed on a metal surface predict the occurrence of various collision induced organic reactions prior to ejection. Lateral motion of particles in the region right above the surface plays an important role in signal enhancement. The calculations predict several processes such as direct molecular ejection, dissociation to fragments, unimolecular rearrangement and hydrogen abstraction reactions.