Does oxidative aging of organic aerosol influence the particle optical properties?
LINDSAY RENBAUM (1), Geoffrey D. Smith (1)
(1) University of Georgia
Abstract Number: 497
Preference: Platform Presentation
Last modified: May 13, 2010
Working Group: Aerosol Chemistry
Tropospheric aerosols have a significant effect on visibility, climate, and the radiation balance in the atmosphere. The optical properties of organic aerosols are poorly understood. However, the organic fraction of ambient aerosols may account for a majority of the aerosol mass in some cases. Accurate measurement of the optical properties of organic aerosols, therefore, is necessary in better understanding these effects as well as for quantifying the influence of aerosols on climate. By using ultraviolet cavity ring down spectroscopy (UV-CRD), we are able to measure the optical extinction (absorption + scattering) from aerosol particles. Using the UV-CRD extinction results and Mie theory, we are able to derive the real and imaginary components of the refractive index of organic aerosols when the particle size and concentrations are known. Using this technique, we are able to observe changes in the aerosol complex refractive index as the organic aerosol particles undergo oxidation reactions analogous to those which occur in the troposphere and we may correlate changes in aerosol optical properties to changes in particle composition due to oxidative aging.