Articles | Volume 11, issue 20
Atmos. Chem. Phys., 11, 10649–10660, 2011
Atmos. Chem. Phys., 11, 10649–10660, 2011

Research article 27 Oct 2011

Research article | 27 Oct 2011

Secondary organic aerosol formation from phenolic compounds in the absence of NOx

S. Nakao1,2, C. Clark1,2, P. Tang1,2, K. Sato2,*, and D. Cocker III1,2 S. Nakao et al.
  • 1University of California, Riverside, Department of Chemical and Environmental Engineering, USA
  • 2College of Engineering – Center for Environmental Research and Technology (CE-CERT), 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 under low NOx conditions. The SOA densities tend to be initially as high as approximately 1.8 g cm−3 and eventually reach the range of 1.3–1.4 g cm−3. The final SOA density was found to be independent of elemental ratio (O/C) indicating that applying constant density (e.g., 1.4 g cm−3) to SOA formed from different aromatic compounds tested in this study is a reasonable approximation. Results from a novel on-line PILS-TOFMS (Particle-into-Liquid Sampler coupled with Agilent Time-of-Flight Mass Spectrometer) are reported. Major signals observed by the on-line/off-line Agilent TOFMS indicated that products had the same number of carbon atoms as their parent aromatics, suggesting importance of ring-retaining products or ring-opening products following ring-cleavage.

Final-revised paper