Reactive scattering of ground-state and electronically excited oxygen atoms on a liquid hydrocarbon surface

Abstract

We have directed a supersonic beam of atomic oxygen containing a large concentration of ground-state O(³P) and a small percentage of electronically excited O(¹D) at a continuously refreshed liquid film of a long-chain saturated hydrocarbon, squalane (C₃₀H₆₂). Angularly resolved flux and energy distributions of reactively scattered products revealed that the dominant volatile reaction product is the OH radical, which can be formed by an Eley–Rideal direct-reaction mechanism or by a process that leads to trapping and desorption of the initial product. Both of these processes occur with comparable probabilities. A second product, 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, although the thermal mechanism dominates.

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