Event

Abstract:

 

Dark chemistry aqueous-phase secondary organic aerosol (aqSOA) products of carbonyl-containing volatile organic compounds (CVOCs) have been observed to be light absorbing and surface-active, resulting in potential contributions to both direct and indirect effects to atmospheric aerosol radiative forcing. While the formation and property effects of these products have been extensively studied for multiple CVOC-containing reaction systems, the chemistry of these same compounds under irradiated (daytime) conditions is much less understood. This presentation explores property measurements of aged CVOC/ammonium-sulfate aerosol mimic solutions under irradiated conditions. Samples exposed to UV radiation exhibited dramatic shifts in surface activity and UV-visible absorbance compared to non-irradiated samples, yielding products indicative of both photolytic and photobrowning chemistry. The observation of photochemically-driven browning phenomena in addition to photobleaching implies that more nuanced approaches may be necessary to fully encapsulate aqueous aerosol chemistry under daytime conditions.