Abstract View
Molecular Characterization of Brown Carbon Produced from the OH/NOx Photo-oxidation of Naphthalene
KYLA SIEMENS, Ana Morales, Anusha P.S. Hettiyadura, Quanfu He, Chunlin Li, Yinon Rudich, Alexander Laskin, Purdue University
Abstract Number: 426
Working Group: Aerosol Chemistry
Abstract
Brown carbon (BrC) has been identified as a class of secondary organic aerosol (SOA) constituents with substantial light-absorption in the visible light range that influences regional visibility and radiative forcing of the climate. In this study, we investigate the chemical composition of BrC formed during the photo-oxidation of naphthalene, a polyaromatic hydrocarbon emitted during fossil fuel combustion, in the presence of OH and NOx (NO + NO2). We provide molecular insights to the effect of atmospheric ageing on optical properties of the BrC components of this system. We employ high performance liquid chromatography equipped with a photodiode array detector and a high-resolution mass spectrometer (HPLC-PDA-HRMS) to determine the chemical composition of naphthalene-derived SOA and its BrC constituents formed in the presence of NOx. Results of this work reveal the buildup of highly absorbing nitro-aromatic chromophores formed in high NOx environments, and the extent of their degradation during processes of atmospheric ageing. This research contributes to the development of high performance and high-resolution techniques for the structural elucidation of strongly absorbing organic aerosol, specifically BrC chromophores. This project also contributes to a predictive understanding of the processes and conditions that form BrC from anthropogenic aromatic hydrocarbons.