Dynamics of NO reduction by H-2 on Rh(111): Velocity and angular distributions of the N-2 product

The velocity and angular distributions of N-2 produced from the reduction of NO by H-2 on Rh(111) have been measured in the low nitrogen coverage limit as a function of surface temperature. Both the angular and velocity distributions are well fit by bimodal forms. The high energy channel has average translational energies about six times that expected for molecules accommodated at the surface temperature, an unusually sharp angular distribution, and angle dependent velocity distributions. The low energy channel is also hyperthermal, with average translational energies about twice thermal, a cosine angular distribution, and velocity distributions which are independent of angle. Application of surprisal analysis to the data shows that the high energy channel may be characterized by constraints on the normal velocity and the total energy; the low energy channel may be characterized by a single constraint on the velocity. (C) 1996 American Institute of Physics.