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

A Pd(110) surface was exposed to a constant flow of a (NO + CO) mixture. Rates of N-2, 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. N-2 desorption showed a two-directional desorption approximated by cos(28)(0 +/- 41 degrees), while N2O followed a simple cos a distribution, showing complete accommodation to the surface temperature. CO2 desorption was collimated in the surface normal direction, described by cos(15) theta accompanied by a cos theta component. Desorbing Nz 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. (C) 2000 Elsevier Science B.V. All rights reserved.