The acetyl peroxy radical (CH3C(O)O2) is a key intermediate in the oxidation of carbonyl-containing hydrocarbons in the troposphere. Reaction of acetyl peroxy radicals with HO2 has been suggested as a source of OH radicals in low-NOx conditions. Previous work on this reaction observed only two product channels forming (1) peracetic acid and (2) acetic acid. Recent experiments have shown that there is a third channel that generates the radicals OH and acetoxy:  CH3C(O)O2 + HO2 ? (1) CH3C(O)OOH + O2 (2) CH3C(O)OH + O3 (3) CH3C(O)O + O2 + OH  This last pathway to OH formation would then contribute to the apparent isoprene OH recycling suggested by discrepancies between atmospheric models and field observations of OH. There have, however, been significant disagreements among experiments on the yield of OH in this reaction.  We report our preliminary studies of acetyl peroxy reaction with itself and HO2. Experiments were conducted at the Advanced Light Source synchrotron at the Lawerence Berkeley National Laboratory using tunable VUV ionizing radiation coupled to the Sandia National Laboratory pulsed-laser-photolysis multiplexed photoionization mass spectrometer to detect time-resolved photofragmets of reactants, intermediates, and products. From these results, we report new values for the branching fractions of the three product channels in the acetyl peroxy + HO2 radical reaction.

Kinetics and product yields of the acetyl peroxy + HO<sub>2</sub> radical reaction studied by photoionization mass spectrometry

247th National Meeting (2014)

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Kinetics and product yields of the acetyl peroxy + HO2 radical reaction studied by photoionization mass spectrometry

Kinetics and product yields of the acetyl peroxy + HO₂ radical reaction studied by photoionization mass spectrometry