Desorption of products in 193 nm photo-induced reactions in (O2 + CO) adlayers on Pt(112)
Abstract
The spatial distributions of desorbing products were examined in 193 nm photo-induced reactions in O2 + CO adlayers on stepped Pt(112) = [(s)3(111) × (001)]. At high coverage of O2(a) and CO(a), both O2 and CO2 desorption collimated closely along the (111) terrace normal. The results were compared with those in thermal CO oxidation, and the origin of the collimation angle shift in the latter is discussed. On the other hand, at low CO(a) coverage, O2 and CO2 desorption collimated in inclined ways in the plane along the surface trough. At these collimation positions, the kinetic energy of desorbing O2 and CO2 was maximal, confirming the hot-atom collision mechanism.