Quasi-classical trajectory study of Si+O2-->SiO+O reaction.

Quasi-classical trajectory calculations for the Si(P3)+O2(XΣg−3)→SiO(XΣ+1)+O(D1) reaction have been carried out using the analytical ground A′1 potential energy surface (PES) recently reported by Dayou and Spielfiedel [J. Chem. Phys. 119, 4237 (2003)]. The reaction has been studied for a wide range of collision energies (0.005–0.6eV) with O2 in its ground rovibrational state. The barrierless PES leads to a decrease of the total reaction cross section with increasing collision energy. It has been brought to evidence that the reaction proceeds through different reaction mechanisms whose contributions to reactivity are highly dependent on the collision energy range. At low collision energy an abstraction mechanism occurs involving the collinear SiOO potential well. The associated short-lived intermediate complex leads to an inverted vibrational distribution peaked at v′=3 and low rotational excitation of SiO(v′,j′) with a preferentially backward scattering. At higher energies the reaction proceeds mainly thr...