Oxidation of H on Rh(111): H2O product velocity and angular distributions

The translational energy distribution for the H2O product from the reaction of H2 and O2 on Rh(111) was measured as a function of surface temperature at two different oxygen coverages. The results are well represented by Maxwell–Boltzmann velocity distributions significantly cooler than the surface temperature. For [O]=0.2 monolayers (ML), the product H2O is slightly faster than for [O]=0.1 ML. The energy distributions are very close to those observed for the trapped and desorbed molecules when scattering low energy H2O molecular beams from the Rh(111). We also measured the angular dependence of the energy and intensity of the product H2O at Ts=650 K. The velocity distribution of the H2O product is independent of final angle, and the relative intensities are cosine distributed.