Our atmospheric chemistry research involves both development of new analytical techniques for the study of atmospheric pollution and application of these techniques in ambient and indoor environments. We recently studied the causes of visibility reduction in Class I Visibility Regions (national parks). We characterized the size-dependent chemical composition of aerosols in the atmosphere and investigated the chemistry leading to aerosol formation. We developed methods for tracing pollutants during long-range transport using receptor-based, chemical mass balance, source apportionment methods to determine the contributions of various sources to observed pollutants and the effect of these pollutants on visibility. We have developed sampling methods, including state-of-the-art diffusion denuder sampling techniques, for the accurate chemical characterization of organic material in fine particles as a function of particle size. We are currently studying the formation of semivolatile organic compounds from the chemistry of NO_x and organic material in the atmosphere. We use a variety of analytical techniques: e.g., capillary column gas chromatography, supercritical fluid chromatography, mass spectroscopy, ion chromatography, proton induced X-ray emission analysis, scanning electron microscopy, and temperature-programmed organic volatilization. A 30 m³ Teflon chamber with dedicated instrumentation for the real-time determination of aerosol composition is used in model studies of air pollution.

     A second research area is the application of thermodynamics to the understanding of the properties of aerosols. Current research is related to the thermodynamic properties of, and molecular interactions in, concentrated solutions that model atmospheric acidic sulfate/organic compound aerosols.