Volatile organic compounds (VOC) are emitted into the atmosphere from biogenic and anthropogenic sources. They subsequently react primarily with OH radicals, NO3 radicals, or O3 via reactions that can affect the formation of O3 and secondary organic aerosol (SOA). Alkoxy radicals are important intermediates in these reactions that can either react with O2 to form carbonyls, isomerize to form multifunctional products, or decompose to form (for non-cyclic radicals) a pair of smaller fragmentation products. The branching ratios for these three pathways depend on the length of the carbon chain, chain branching, and the presence and location of functional groups. Although reaction pathways that lead to the addition of functional groups to the parent VOC enhance the tendency for reaction products to form SOA, these functional groups also enhance the tendency for alkoxy radicals formed in subsequent oxidative aging reactions to decompose to more volatile products that are less likely to form SOA. The development of models for predicting the fate of VOCs and SOA formation thus depends on a quantitative understanding of these reaction pathways. In this talk will I will discuss results of environmental chamber studies in which we have quantified the branching ratios for isomerization and decomposition (O2 reactions are unimportant) of �-hydroxyalkoxy radicals formed from the reaction of 2-methyl-1-alkenes with OH radicals in the presence of NOx, and �-nitrooxyalkoxy radicals formed from the reactions of NO3 radicals with 1-alkenes. These results will also be compared with predictions based on structure-activity relationships and computational methods.

Experimental study of the effects of functional groups on the decomposition of alkoxy radicals formed from reactions of alkenes with OH and NO<sub>3</sub> radicals

248th National Meeting (2014)

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Experimental study of the effects of functional groups on the decomposition of alkoxy radicals formed from reactions of alkenes with OH and NO3 radicals

Experimental study of the effects of functional groups on the decomposition of alkoxy radicals formed from reactions of alkenes with OH and NO₃ radicals