Abstract View
Nucleation and Growth of Particulate Matter from the Photooxidation of Aromatic Hydrocarbons
ISSAK PROAÑO LÓPEZ, Murray Johnston, University of Delaware
Abstract Number: 457
Working Group: Aerosol Chemistry
Abstract
The oxidation of volatile organic compounds (VOCs) in the atmosphere to produce low-volatility products that form secondary organic aerosol (SOA) through the nucleation and growth of nanoparticles is of great atmospheric importance. The majority of VOCs present in the atmosphere are of biogenic origin, however, in the industrial period the proportion of VOCs emitted from anthropogenic activities has increased, especially in areas where urbanization and industrialization are prevalent.
Anthropogenic VOCs that produce low-volatility products are typically from the aromatic hydrocarbon class, whose dominant oxidation mechanism in the atmosphere involves the hydroxyl radical (∙OH). We are using multiple flow-through photooxidation chambers to generate ∙OH for the study of particle nucleation and growth from anthropogenic VOCs. In initial work, the molecular composition of anthropogenic SOA is being characterized online by droplet-assisted ionization (DAI) interfaced with a Waters Synapt G2-S quadrupole ion mobility time-of-flight mass spectrometer and offline by particle collection and analysis by electrospray ionization (ESI) interfaced with an Orbitrap mass spectrometer. Particle-phase composition is reconciled with measurements of gas-phase oxidation products that have been previously reported using chemical ionization mass spectrometry. The results give insight into the mechanism of particle growth in an urbanized environment.