. Theoretical dynamics study of several atomic and molecular oxygen processes over a silica surface

R. SAYÓS; V. MORÓN; C. ARASA; H.F. BUSNENGO

Versalles, Francia

Simposio; 6th European Symposium on Aerothermodynamics for Space Vehicles; 2008

The reaction dynamics of both molecular oxygen on clean β-cristobalite (100) and atomic oxygen O with O atoms preadsorbed onto the same surface are investigated by means of the quasiclassical trajectory method using an ab initio interpolated full dimensionalpotential energy surface based in a large grid of density functional theory points. Trajectories are computed for several state-specific conditions: collision energies(0.05-4 eV), surface temperatures (300, 1100 K), incident angles (0-60º), internal (v,j) states of O2, etc. Several possible processes are examined in detail for both reactions. Reflection and non-dissociative sticking are the main channels for O2 scattering; the dissociativechannel becomes only open at high collision energies, and it is essentially promoted in the regions close to the Si atoms of the first layer of slab. O sticking is the main process for O scattering; reflection and Eley-Rideal (ER) reaction probabilities have different extension depending on the initial conditions of reactants. Final ER O2 molecules remain principally stuck to the slab.