Thursday, 12 November 2009: 1:55 PM
The reaction between HO2 and RO2 radicals represents an important chemical sink for HOx radicals in the troposphere. On the basis of a few studies, several carbonyl-containing organic peroxy radicals may react via three different channels. (R1a-c): RO2 + HO2 → ROOH + O2 (R1a), RO2 + HO2 → ROH + O3 (R1b), RO2 + HO2 → RO + O2 + OH (R1c). The relative yields of these products may play a role in both air quality and climate change. To evaluate whether these reactions are a general feature of carbonyl-containing peroxy radicals, branching ratios for Reaction R1 were measured for four species: butionyl peroxy (CH3(CH2)2C(O)O2), isobutionyl peroxy (CH3C(CH3)HC(O)O2), pentionyl peroxy (CH3(CH2)2C(O)O2), and 2,4-dimethyl-3-pentionyl-2-peroxy (CH3C(CH3)(O2)C(O)C(CH3)HCH3) radicals. Product yields were measured using a combination of Fourier transform infrared spectroscopy, high-performance liquid chromatography with fluorescence detection, gas chromatography with flame-ionized detection, and gas chromatography with mass spectrometry. The atmospheric implications of the results will be discussed.
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