Distinguishing the Direct and Indirect Products of a Gas-Surface Reaction
Charles T. Rettner 1 and
Daniel J. Auerbach 1
1 IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120
It has long been postulated that gas-surface chemical reactions can occur by means of two distinct mechanisms: direct reaction on a single gas-surface encounter or reaction between two adsorbed species. It is shown here that these mechanisms have distinct dynamical signatures, as illustrated by the reaction of hydrogen with chlorine on gold(111). The direct reaction product leaves the surface with a high kinetic energy in a narrow angular distribution that displays a "memory" of the direction and energy of the incident hydrogen atom. The indirect reaction product has a near-thermal energy distribution and an angular distribution that is close to that of a cosine function.
Submitted on September 27, 1993
Accepted on November 17, 1993
