Photochemical smog, characterized by the formation of atmospheric oxidants, results from the oxidation of volatile organic carbon (VOC) in the presence of the oxides of nitrogen (NOx) and sunlight. Our group is primarily interested in the photochemical transformations of organic compounds in the lower atmosphere during smog production. Of particular interest is incorporation of oxides of nitrogen into secondary organic photoproducts such as peroxyacetyl nitrate (PAN) and alkyl nitrates. We attempt to understand the reactivity of individual organic compounds, the pathways of reactions, and the impact of these compounds on the regional and global atmosphere.
We accomplish our goals through a variety of methods, all of which are subjects of current projects:
- deployment of instrumentation for measurement of ambient air
- laboratory studies of specific reactions and products
- interpretation of data from collaborative measurement experiments
We have been involved in collaborative projects like the Southern Oxidants Study (SOS), the North Atlantic Regional Experiment (NARE), Program for Research on Oxidants: PHotochemistry, Emissions, and Transport (PROPHET), Community Atmosphere-Biosphere Interactions Experiments (CABINEX) and the New England Air Quality Study (NEAQS).
One focus relates to the contribution of naturally-occurring organic compounds, such as isoprene, relative to human pollution from sources such as automobile exhaust. We are involved in the effort to elucidate the photochemical mechanism of isoprene oxidation by looking at the range of organic products both in ambient air an in smog chamber experiments.