Crossed beam reaction of the phenyl radical, (C6H5, X2A′) with molecular oxygen : Observation of the phenoxy radical, (C6H5O, X2A′)

The chemical dynamics of the combustion-relevant reaction of phenyl radicals with molecular oxygen were investigated in a crossed beam reaction at a collision energy of 107 kJ mol−1. Under these conditions, the formation of the phenoxy radical (C6H5O) plus ground state atomic oxygen was observed; no atomic hydrogen exchange pathway was opened. The reaction dynamics of the phenoxy radical channel were found to be direct, involved a stripping-like reaction mechanism, and were initiated by a radical–radical recombination of phenyl plus molecular oxygen forming a short lived phenylperoxy radical (C6H5O2). The latter decomposed to the phenoxy radical plus atomic oxygen; the overall reaction was exoergic by about 38 ± 15 kJ mol−1.