Spectroscopy and photochemistry of organic constituents of atmospheric aerosols

Brown carbon aerosol in Earth’s atmosphere absorbs solar radiation at visible wavelengths and contributes to the overall warming of the troposphere. It is released directly to the atmosphere by biomass burning, whether from wild fires, domestic fuels, or agricultural practices, and degrades air quality. Brown carbon aerosol particles contain a complex matrix of organic constituents, of which the most significant contributors to absorption of near-UV and visible light are nitroaromatic compounds such as nitrophenols and nitrocatechols. This talk will describe: (i) determination of the optical properties of aqueous aerosols containing example nitroaromatic compounds using single-particle cavity ring-down spectroscopy (CRDS), and (ii) exploration of the photochemistry of aqueous nitroaromatic compounds over femtosecond to microsecond timescales using transient absorption spectroscopy.