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Atmos. Chem. Phys. Discuss., 11, 2025-2055, 2011
www.atmos-chem-phys-discuss.net/11/2025/2011/ doi:10.5194/acpd-11-2025-2011 © Author(s) 2011. This work is distributed under the Creative Commons Attribution 3.0 License. |
Secondary Organic Aerosol formation from phenolic compounds in the absence of NOx
1University of California, Riverside, Department of Chemical and Environmental Engineering, Riverside, California, USA
2College of Engineering – Center for Environmental Research and Technology (CE-CERT), Riverside, California, USA
*currently at: National Institute for Environmental Studies, Japan
Abstract. SOA formation from benzene, toluene, m-xylene, and their corresponding phenolic compounds were investigated using the UCR/CE-CERT Environmental Chamber to evaluate the importance of phenolic compounds as intermediate species in aromatic SOA formation. SOA formation yield measurements coupled to gas-phase yield measurements indicate that approximately 20% of the SOA of benzene, toluene, and m-xylene could be ascribed to the phenolic route. The SOA densities tend to be initially as high as approximately 1.8 g/cm3 and eventually reach the range of 1.3–1.4 g/cm3. The final SOA density was found to be independent of elemental ratio (O/C) indicating that applying constant density (e.g., 1.4 g/cm3) to SOA formed from different aromatic compounds is a reasonable approximation. Results from a novel on-line PILS-ToF (Particle-into-Liquid Sampler coupled with Agilent Time-of-Flight) are reported. Major signals observed by the on-line/off-line ToF include species consistent with bicyclic hydroperoxides. To the authors' best knowledge, this is the first possible detection of bicyclic hydroperoxides in aromatic SOA.
Citation: Nakao, S., Clark, C., Tang, P., Sato, K., and Cocker III, D.: Secondary Organic Aerosol formation from phenolic compounds in the absence of NOx, Atmos. Chem. Phys. Discuss., 11, 2025-2055, doi:10.5194/acpd-11-2025-2011, 2011.