Gas-Surface Interactions of Importance to Particle Formation and Growth in Air

Abstract:

Interactions of gases with the condensed phase of airborne particles in the troposphere play an important role in air quality, climate, visibility and deleterious health impacts. However, for most of these interactions, a fundamental mechanistic understanding of the chemistry is lacking. Without this, the development of models that have sufficiently accurate predictive capability on scales from local to regional to global is severely hampered. Studies of the interactions of gas phase organics with bulk condensed phases that are proxies for secondary organic aerosol (SOA) and for "urban grime" on boundary layer surfaces will be presented. These use a combination of techniques, including attenuated total reflectance-Fourier transform infrared spectrometry (ATR-FTIR) and a flow system coupled to a mass spectrometer. The results of studies of the interactions of gas phase organics with clusters of methanesulfonic acid, amines and water using a flow system combined with measurements of the time dependence of particle size distributions and mass spectrometry will also be described. The outcome of these studies is an improved understanding of how SOA is formed and grows, as well as the heterogeneous chemistry of organics on urban surfaces.