Carbon monoxide oxidation on Rh(111): Velocity and angular distributions of the CO2 product

The velocity and angular distributions of CO2 produced by CO oxidation on Rh(111) have been measured as a function of surface temperature and oxygen coverage. Both the velocity and angular distributions are bimodal. The velocities of one component are well fit by a Maxwell–Boltzmann distribution at the surface temperature, and the angular distribution of its intensity is cosine. The second component is non-Boltzmann, and the angular distribution is sharply peaked toward normal. The average energy of this feature is a very strong function of the surface temperature, increasing with a slope of 8.7kb, where kb is the Boltzmann constant, between 475 K and 700 K. Surprisal analysis proves useful in condensing and interpreting these data.