REACTIVE SCATTERING OF GROUND-STATE AND ELECTRONICALLY EXCITED OXYGEN-ATOMS ON A LIQUID-HYDROCARBON SURFACE

We have directed a supersonic beam of atomic oxygen containing a large concentration of ground-state O(P-3) and a small percentage of electr onically excited O(D-1) at a continuously refreshed liquid film of a l ong-chain saturated hydrocarbon, squalane (C30H62). Angularly resolved flux and energy distributions of reactively scattered products reveal ed that the dominant volatile reaction product is the OH radical, whic h can be formed by an Eley-Rideal direct-reaction mechanism or by a pr ocess that leads to trapping and desorption of the initial product. Bo th of these processes occur with comparable probabilities. A second pr oduct, H2O, is thought to be formed by abstraction of a hydrogen atom from the hydrocarbon chain by the primary OH product. The H2O product also exits the surface via non thermal and thermal mechanisms, althoug h the thermal mechanism dominates.