Rate equations for collision-induced desorption and abstraction in the reaction system H(g)+D/Si(100)→D2,HD at 573 K

Collision-induced desorption (CID) and Eley–Rideal (ER) type abstraction have been investigated in the reaction system, H(g)+Dad/Si(100)→D2,HD, at surface temperature of 573 K where dihydride phase is unstable. Rate equations for CID were obtained based on a second-order kinetics with respect to doubly occupied Si dimers DSi–SiD, DSi–SiH, and HSi–SiH, which are considered as parent species of transiently formed dihydrides, DSiD, DSiH, and HSiH, respectively. The coverages of the doubly occupied dimers were determined as a function of H exposure time by means of temperature-programmed-desorption (TPD), and then the rate equations were calculated. As a result, the experimental D2 and HD rate curves were reasonably fit with the rate equations formulated. This fact indicates that CID is induced when two dihydride species encounter during their propagation via dihydride–monohydride isomerization reactions. It was found that HSi–SiH does not play a role in CID of both D2 and HD. Possible origins of this isotope...