AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
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Gas and Particle Phase Products of the Reactions of 1-Alkenes with OH Radicals in the Presence of NO
JULIA BAKKER-ARKEMA, Paul Ziemann, University of Colorado
Abstract Number: 442 Working Group: Aerosol Chemistry
Abstract Controlled environmental chamber studies are important for determining atmospheric reaction mechanisms and gas and aerosol products formed in the oxidation of volatile organic compounds (VOCs). Such information is necessary for developing detailed chemical models for use in predicting the atmospheric fate of VOCs and also secondary organic aerosol (SOA) formation. In this work, we explored the reaction of 1-tetradecene [CH3(CH2)11CH=CH2] with OH radicals in the presence of NO as a model for the oxidation of alkenes, which are the dominant components of non-methane biogenic VOC emissions to the atmosphere. Particle-phase products were analyzed in real time with a thermal desorption particle beam mass spectrometer, and off-line by collection onto filters and subsequent analysis of functional groups by derivatization-spectrophotometric methods developed in our lab. Derivatized products were also separated by liquid chromatography for molecular quantitation by UV absorbance and identification using chemical ionization-ion trap mass spectrometry. Gas phase aldehydes were analyzed in real time with a proton transfer-reaction mass spectrometer and off-line by collection and derivatization on a 5-channel denuder and subsequent analysis by gas chromatography. Previous work in this lab has quantified the yields of beta-hydroxynitrates and dihydroxynitrates, and here we quantified the other two major expected products: tridecanal and dihydroxycarbonyls, which are formed by decomposition and isomerization of alkoxy radical intermediates. Tridecanal was also studied with regards to its potential role in particle-phase formation of hemiacetals, and a potential contribution to SOA from unexpected carboxylic acid products was investigated. Together, the gas and particle phase measurements provide a more comprehensive view of the mechanism of alkene oxidation and SOA formation.