Hygroscopicity of ultrafine organic aerosol particles: The role of chemical composition and structure

COLL 19

Ahmad Alshawa, aalshawa@uci.edu1, Joelle Underwood2, Sergey Nizkorodov, nizkorod@uci.edu1, and Steven Ng3. (1) Department of Chemistry, University of California at Irvine, 516 Rowland Hall, Irvine, CA 92697, (2) Department of Chemistry, University of California, 1102 Natural Sciences II, Irvine, CA 92697, (3) University of California, Irvine
Extensive oxidation of organic particles may play a role in converting them to efficient cloud condensation nuclei (CCN). Electrospray aerosol generation yields organic aerosol particles with a narrow size distribution (< 100 nm, gsd ~ 1.2). Characterization of the aerosol particles using surface imaging techniques shows structures are consistent with those observed for condensed phase regular micelles (electrospray of surfactant in excess polar solvent)and inverted micelles (electrospray of surfactant with excess nonpolar solvent). Surfactants used to generate model organic aerosols include oleic acid, AOT, and SDS. Water uptake studies are performed to investigate the hygroscopic properties of organic aerosols with inverted micelle, regular micelle, and disordered structures. The change in size of the organic particles as a function of relative humidity is monitored using a dynamic mobility analyzer. Organic aerosol particles are oxidized and the resulting effect on their hygroscopicity is probed in water uptake experiments.
 

Environmental Interfaces
8:30 AM-12:00 PM, Sunday, 10 September 2006 Sir Francis Drake -- Empire Room, Oral

Division of Colloid & Surface Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006