Removal pathways of surface nitrogen in a steady-state NO + CO reaction on Pd(110) and Rh(110): Angular and velocity distribution studies

The angular and velocity distributions of desorbing products N₂ and O₂ were studied in a steady-state NO + CO reaction on Pd(110) and Rh(110) by cross-correlation time-of-flight techniques. The CO₂ desorption sharply collimated along the surface normal on both surfaces. On the other hand, N₂ desorption on Pd(110) sharply collimated along about 40° off the surface normal in the plane along the [001] direction below around 650 K, yielding a translational temperature of about 3600 K. At higher temperatures, the normally directed desorption was relatively enhanced. On Rh(110), desorbing N₂ sharply collimated along the surface normal, yielding a translational temperature of about 2500 K. The inclined desorption was assigned to the decomposition of the intermediate, N₂O(a) → N₂(g) + O(a), and the normally directed component was proposed to be due to the associative desorption of adsorbed nitrogen atoms, 2N(a) → N₂(g). The branching of these pathways was analyzed on Pd(110).