AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
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Optical Properties of Secondary Organic Aerosols from Oxidation of alpha-pinene, toluene, and 1-methylnapthalene
JUSTIN MIN, Stephen Zimmerman, Justin Dingle, Roya Bahreini, University of California, Riverside
Abstract Number: 663 Working Group: Aerosol Physics
Abstract Although many sources of secondary organic aerosol (SOA) precursors are identified, the optical properties of SOA formed in the atmosphere are not well characterized. In this investigation, we will focus on calculating optical properties such a single scattering albedo (SSA), Angstrom exponents of extinction (A$_(ext)), mass absorption coefficients (MAC), and mass extinction coefficients (MEC) of SOA produced from the oxidation of alpha-pinene, toluene, and 1-methylnapthalene. We will relate changes in chemical characteristics of the SOA to the observed changes in the optical properties. Precursors will be oxidized by OH radicals generated from H$_2O$_2 and HONO photolysis or Cl radicals from Cl$_2 gas in a Teflon chamber with black lights radiating at 350 nm. Furthermore, reactions will be carried out with variable precursor concentrations, relative humidity, and nitrogen oxide levels to mimic different atmospheric oxidation conditions. Optical properties will be characterized using a Cavity Attenuated Phase shift extinction monitor (CAPS-PM$_(ex)) which measures the optical extinction coefficients at 632 nm while a Photoacoustic Extinctiometer (PAX-375) will be used to measure the absorption and scattering coefficients at 375 nm. The CAPS-PM$_(ex) paired with the PAX-375 will help us to determine MEC's at 375 nm and 632 nm, mass absorption and scattering coefficients and SSA at 375 nm, and A$_(ext) of the SOA.