AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Formation of Secondary Organic Aerosol by the Direct Photolytic Generation of Alkoxy Radicals
ANTHONY CARRASQUILLO, Sean Kessler, Theodora Nah, Kevin Wilson, Douglas Worsnop, Jesse Kroll, MIT
Abstract Number: 607 Working Group: Aerosol Chemistry
Abstract Our understanding of the chemistry of secondary organic aerosol (SOA) formation from precursor organic compounds 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 (and oxidation generation) 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. Environmental chamber experiments with a series of straight chain (C4 – C10) alkyl nitrites were conducted to investigate how the position of the radical species along the carbon backbone influences SOA yields. The distribution of the major product species from each precursor species was determined using an Aerodyne Aerosol Mass Spectrometry (utilizing electron impact ionization and vacuum ultraviolet photoionization techniques) and off-line liquid chromatographic techniques. The time-evolution of individual product species are considered in the context of product yields and gas-particle partitioning, providing new insight into SOA formation from alkanes, and in particular highlighting the important role of minor pathways in SOA formation chemistry.