Eley-rideal reactions with N atoms at Ru(0001): formation of NO and N(2).

Forward-directed NO molecules with large translational energies are formed upon exposure of an O-covered Ru(0001) surface to a nitrogen (N+N_{2}) beam. This is an unequivocal experimental demonstration of the Eley-Rideal reaction for a "heavy" (i.e., nonhydrogenated) neutral system. The time dependence of prompt NO formation exhibits an exceptionally fast decay as a consequence of shifting reaction pathways and probabilities over the course of the exposure. Prompt production shuts down as the O coverage decreases due to competition from more favorable Eley-Rideal production of N_{2}.