Abstract View
Nucleation and Growth of Particulate Matter from Aromatic Hydrocarbons Using a Photooxidation Flow Tube
ISSAK PROAÑO LÓPEZ, Murray Johnston, University of Delaware
Abstract Number: 567
Working Group: Aerosol Chemistry
Abstract
The formation of secondary organic aerosol (SOA) via the nucleation and growth of nanoparticles from the photooxidation of anthropogenic volatile organic compounds (AVOCs) is of increasing atmospheric interest. Despite most volatile organic compounds in the atmosphere being of biogenic origin, an increasing presence of AVOCs from human activities during the industrial period has led to a corresponding increase in SOA formation in and around areas where urbanization and industrialization abound. AVOCs exhibit the ability to produce particulate matter of their own while simultaneously enhancing the production of SOA from biogenic precursors.
AVOCs that produce low-volatility products are traditionally of the aromatic hydrocarbon class, and the dominant oxidation mechanism these exhibit in the atmosphere involves the hydroxyl radical (∙OH). A flow tube-type photooxidation reactor is designed and constructed to generate ∙OH for the study of particle nucleation and growth from AVOCs while approximating real-world atmospheric conditions. Previous work saw the molecular composition of anthropogenic SOA characterized in an online fashion using droplet-assisted ionization (DAI) interfaced with a Waters Synapt G2-S quadrupole ion mobility time-of-flight mass spectrometer. In this study, extractive droplet-assisted ionization (E-DAI) will combine the benefits afforded by electrospray ionization (ESI) with the online abilities afforded by DAI, and interface these with the Waters Synapt G2-S to characterize molecular composition. Particle-phase composition of aerosol produced in the photooxidation flow tube will be reconciled with previous work using traditional DAI, offline analysis using ESI, and gas-phase oxidation products previously reported using chemical ionization mass spectrometry. The results will afford insight on the mechanisms of particulate growth in urbanized environments.