Classical trajectory treatment of diatomic molecules reacting with solid surfaces: a study of mass effects

Abstract

Abstract The mechanism of the rection between the diatomic molecule and a solid non-corrugated surface has been studied, employing the classical trajectory method. The study was performed in the energy range 1–6 eV, where all four types of collisions, inelastic, reaction (dissociative trapping), adsorption and dissociation, take place. To study mass effects three kinds of diatomic molecules were considered: the light—light (LL) mass combination represented by H 2 , the light—heavy (LH) mass combination representedby HCl and HI and the heavy—heavy(HH) mass combination represented by Cl 2 and I 2 . The main findings are: (a) The reactive process for the LL and HH systems is governed by one reaction mechanism, and those for the LH systems are governed by two different mechanisms. (b) Whereas the LL and HH systems tend to dissociate upon collision with the surface, once threshold for dissociation is reached no dissociation is encountered for the LH systems, even for energies of tens of electron volts. (c) The gas/3-solid-phase reactive process differs significantly from that encountered in the gas phase in that the important gas-phase quasicollinear arrangements play a negligible role in the gas—solid phase.