Reaction sites in thermo- and photo-induced CO oxidation on stepped Pt(113) and the collimation of product desorption

The reaction sites in the thermal and photolytic CO oxidation on Pt(s)2(111)x(001) were examined through analysis of the angular and velocity distributions of desorbing product CO2. In the former, the CO2 desorption is sharply collimated but fairly shifted from the site normal, although the reaction proceeds on hollow sites of (100) and (111) patches. On the other hand, CO2 produced in the photo-reaction is desorbed sharply along the (100) and (111) plane normal. This difference in the collimation is explained by reducing surface smoothing effect due to high velocity of desorbing CO2.