Photochemistry of secondary organic aerosol particles formed in oxidation of monoterpenes by O3 and NO3

ENVR 6

Sergey Nizkorodov, nizkorod@uci.edu1, Adam Bateman, abateman@uci.edu1, Stephen Mang, samng@uci.edu1, Xiang Pan, xpan@uci.edu1, Joelle Underwood1, Maggie Walser, mwalser@uci.edu1, Jiahua Xing1, Yuri Dessiaterik, yury.desyaterik@pnl.gov2, Alexander Laskin, Alexander.Laskin@pnl.gov2, and Julia Laskin, Julia.Laskin@pnl.gov3. (1) Department of Chemistry, University of California, 1102 Natural Sciences II, Irvine, CA 92697, (2) Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354, (3) Chemical and Materials Sciences, Pacific Northwest National Laboratory, P.O. Box 999 K8-88, Richland, WA 99352
Secondary organic aerosol (SOA) is formed by oxidation of volatile organic compounds (VOCs). After SOA forms, reactions occurring inside the particles further change their chemical composition. This research focuses on the mechanisms of direct photodissociation processes taking place inside SOA particles generated by oxidation of monoterpenes by O3 and NO3 studied with cavity ring-down spectroscopy and mass-spectrometry. The SOA extracts are all found to absorb a significant amount of radiation in the tropospheric actinic window. This absorption photolyzes SOA constituents, resulting in the release of small VOC molecules and change in the SOA chemical composition. The photolytic activity is primarily attributed to organic peroxide, aldehyde and peroxynitrate functionalities. Mass spectra of SOA extracts show evidence for the formation of oligomers during aerosol particle growth. This research demonstrates that direct photochemical processes occurring inside SOA particles change their chemical composition on atmospherically relevant time scales.
 

Atmospheric Aerosol Processes
8:30 AM-11:45 AM, Sunday, August 19, 2007 Boston Park Plaza -- Stanbro Rm, Oral

Division of Environmental Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007