A mechanism for surface catalysis in which the reaction occurs between a reactant molecule in the gas phase and one that is adsorbed on the surface.
Source:
PAC, 1996, 68, 149. 'A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)' on page 171 (https://doi.org/10.1351/pac199668010149)