10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Chlorine and Nitrate Radical Generation in Oxidation Flow Reactors
ANDREW LAMBE, Jordan Krechmer, Ezra Wood, William Brune, Douglas Worsnop, Aerodyne Research, Inc.
Abstract Number: 80 Working Group: Oxidation Flow Reactor: Development, Characterization, and Application to Aerosols
Abstract The majority of oxidation flow reactor (OFR) applications to date involve the generation of hydroxyl (OH) radicals to study daytime multigenerational oxidation of secondary organic aerosol (SOA) precursors. Other atmospheric radicals may also initiate SOA formation, with their relative importance dependent on the specific source region and radical precursor diel profile. Here, we present results from experiments using novel techniques to generate chlorine (Cl) and nitrate (NO3) radicals in the Aerodyne Potential Aerosol Mass OFR for the study of polluted marine and nighttime source regions, respectively. We provide experimental and model evaluation of Cl and NO3 generation capabilities as a function of OFR operating conditions. We use proton transfer reaction and chemical ionization mass spectrometer measurements to characterize precursors and oxidation products generated from the Cl and NO3 oxidation of representative SOA precursors. Finally, we discuss the combined use of OH, Cl and NO3 radicals to (1) evaluate the fate of known SOA precursors under different atmospheric conditions and (2) constrain the composition of unknown SOA precursors with different OH, Cl and NO3-initated oxidation rates and SOA formation potentials.