Surface processes involving nitrogen molecules and atoms on silica surface at low temperature: the role of energy exchanges

The dynamics of elementary surface processes, promoted by nitrogen atoms and moleculesimpacting a silica surface, has been investigated by adopting a semiclassical scatteringmethod. The appropriate treatment of the long-range interaction forces emphasized the crucialcontrol exercised by the weakly bound precursor state on the stereo-dynamics of all basicelementary processes occurring at the gas-surface inter-phase. Molecular dynamicssimulations have highlighted the role of vibrationally excited molecules in plasma dynamics.Indeed, N2 molecules, impinging the surface in low-medium vibrational levels, conserve theinitial vibration state while are inelastically scattered, rotationally excited and translationallycolder. Moreover, N2 molecules nascent from the atomic recombination on the surface have afair probability of forming at very high vibrational levels, with a consistent part of reactionexothermicity transferred to the translational energy. Consequently, the surface induces astrong non-equilibrium condition, influencing directly the dynamics of processes occurring inthe plasma bulk.