AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Insights into SOA Formation Chemistry from the Isolation of Individual Reactive Pathways
ANTHONY CARRASQUILLO, Kelsey Boulanger, James Hunter, Sean Kessler, Kelly Daumit, Jesse Kroll, MIT
Abstract Number: 508 Working Group: Aerosol Chemistry
Abstract Our understanding of the chemistry of secondary organic aerosol (SOA) formation from precursor organic species is hindered by the complexities arising from multiple reaction pathways and generations of oxidation. Here, we constrain radical oxidation chemistry to a single reaction pathway by forming SOA from the direct photolytic generation of alkoxy radicals from alkyl nitrite (RONO) species. Direct photolysis of RONO species yields one specific alkoxy radical, which greatly simplifies the subsequent chemistry by allowing for individual reaction steps and pathways to be examined. Laboratory chamber experiments under added NO conditions (to ensure RO2 + NO chemistry dominates) were conducted with a series of C10 RONO species to investigate how the structure of the parent alkoxy radical species influences the formation of SOA. We examined the role of radical substitution (primary, secondary, and tertiary), radical position along the carbon backbone, and the structure of the carbon skeleton (linear, branched, and cyclic) on SOA formation. SOA yields and the distribution of major products from each precursor species as well as bulk aerosol properties (O/C, H/C, and N/C) were determined using an Aerodyne Aerosol Mass Spectrometer and compared to analogous alkane oxidation experiments. The evolution of individual product species provides new insight into SOA formation from alkanes, and highlights the importance of molecular structure in SOA formation chemistry.