Effect of co-adsorbed CO and reaction temperature on the dynamics of N ₂ desorption under steady-state N₂O-CO reaction on Rh(110)

We have investigated the effect of co-absorbed CO and reaction temperature on the angular distribution of N₂ desorption by N₂O decomposition under the steady state of N₂O-CO reaction on Rh(110). Spatial distributions of desorbing product N₂ emission have been measured at various surface temperatures and CO coverages. The decomposed N ₂ collimates at 48°-61° off normal in the parallel plane to 001 and 110 directions, indicating that adsorbed N₂O just before the decomposition is oriented along the 001 direction. Although the inclined and collimated N₂ desorption is always observed at any steady-state CO coverage and reaction temperature, the shape of the collimated N₂ distribution varied dependent on the co-adsorbed CO coverage. The distribution becomes sharp and shifts toward the surface normal direction with increasing CO coverage. These effects of adsorbed CO on the angular distribution of N ₂ are interpreted by the collision of desorbed N₂ with co-adsorbed CO.