Collision dynamics for the interaction of oxygen atoms and molecules on a silica surface

Reactive and non-reactive processes due to the interaction of oxygen atoms and molecules with silica and silica-based materials are of great importance both for the chemistry at the gas-surface interlayer or in the bulk of the dissociated gas of various laboratories and natural oxygen plasma systems. Of particular interest is the dynamics and energetics of O atom recombination at surface. This reaction is, in fact, exothermic so that part of the exothermic energy can be shared among the internal degrees of freedom of the formed O2 molecules while the remaining part is transferred to the silica surface as heat flux. The energy shearing mechanism depends on the catalytic activity of the silica substrate that controls the dynamics of various chemical-physics processes involving O and O2 at the surface. In this contribution we focus on the dynamics of: 1) O atoms adsorption; 2) O atoms recombination, via Eley-Rideal mechanism; 3) O2 molecule dissociation and deactivation. We performed Molecular Dynamics calculations using the accurate Potential Energy Surface for the interaction of O, O2 with the silica substrate determined by electronic structure calculations in Ref.[1]. The semiclassical collisional method [2] is applied to describe the dynamics of the nuclear motions of the atoms/molecules over the calculated potential energy surface. [1]Rutigliano M., Zazza C., Sanna N., Pieretti A., Mancini G., Barone V. and Cacciatore M. J. Phys. Chem. A 2009, 113, 15366. [2]Billing G. D., Dynamics of Molecule Surface Interactions, John Wiley&Sons, NY, 2000; Cacciatore M. and Billing G.D. Surf.Sci. 1990,232,35