AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Chlorine-initiated SOA Formation from Biogenic VOCs
CHRISTOPHER LIM, Kelsey Boulanger, Jesse Kroll, MIT
Abstract Number: 295 Working Group: Aerosol Chemistry
Abstract Chlorine-initiated oxidation of volatile organic compounds (VOCs) can compete with VOC oxidation by the hydroxyl radical under certain tropospheric conditions, and likely contributes to the formation of secondary organic aerosol (SOA). However, previous laboratory studies of SOA from chlorine-initiated oxidation of VOCs are limited, particularly with regards to the chemical composition of the aerosol. In this work we examine the formation of SOA from Cl atoms plus two biogenic VOCs, alpha-pinene and isoprene, with the aim of determining SOA composition and identifying chemical markers of Cl-initiated chemistry. Experiments were carried out in an environmental chamber, with chlorine radicals generated from the UV photolysis of molecular chlorine. On-line characterization with an Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (AMS) is used to provide information on chemical composition, such as O/C, H/C, Cl/C and major product ions; however, analysis is complicated by the absence of major chlorinated organic peaks and the formation of refractory species, such as tin (IV) chloride, in the AMS mass spectra. In addition to AMS measurements, FTIR is used to detect carbon-chlorine bonds from filter samples taken during chamber experiments.