Peroxy radicals (RO2) are ubiquitous intermediates in the oxidation of volatile organic compounds. Their competing fates govern subsequent free radical chemistry in the troposphere. Reaction of RO2 with nitric oxide (NO) has two product channels: association to an organic nitrate (RONO2) or oxidation/reduction to nitrogen dioxide (NO2) and an alkoxy radical (RO). In this work, we present measurements of the RO2 + NO rate constant at several pressures for peroxy radicals formed in the chlorine-initiated oxidation of ethene, propene, 2-butene, and isoprene. We monitor the decay of peroxy radicals through their weak and structured A-X transition in the near-infrared using cavity ringdown spectroscopy (CRDS) and the simultaneous kinetics and ringdown (SKaR) technique. Chlorine is a minor tropospheric oxidant found in marine regions and its substitution yields insight into the structure and reactivity of RO2? species. We compare our results to prior work in the literature at a fixed pressure and to measurements on hydroxyl-substituted peroxy radicals.

Cavity ringdown spectroscopy of chlorine-substituted peroxy radicals: Reaction kinetics with nitric oxide

248th National Meeting (2014)

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