Angular and velocity distributions of desorbing molecules in steady-state NO+CO reaction on Pd(110)

A Pd(110) surface was exposed to a constant flow of a (NO+CO) mixture. Rates of N2, N2O, and CO2 formation were determined over the surface temperature range from 350 K to 750 K in angular-resolved form in a plane in the [001] direction. N2 desorption showed a two-directional desorption approximated by cos28(θ±41°), while N2O followed a simple cos θ distribution, showing complete accommodation to the surface temperature. CO2 desorption was collimated in the surface normal direction, described by cos15 θ accompanied by a cos θ component. Desorbing N2 molecules were highly energetic as confirmed by velocity distribution measurements in which two components with kinetic energies of 0.46 eV and 0.23 eV were found.