Collaborative research: Linking gas phase precursors with aerosol size, number and composition in new particle formation

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This research will improve the understanding of the formation and growth of very small particles in the atmosphere. This laboratory study will assess the effects of temperature, relative humidity, and the concentrations of gas phase species to the formation and growth rates of small particles. Graduate students will participate in the project and will be exposed to the use of state-of-the-art instrumentation in atmospheric chemistry. The research will be applicable to improving models that predict the formation of cloud condensation nuclei in the atmosphere.The project is organized around three major themes: sulfuric acid nucleation and growth, biogenic new particle formation (NPF) particularly the role of isoprene, and the role of specific oxidants in NPF. The following scientific questions will be addressed: (1) How do temperature and RH affect sulfuric acid nucleation rates, especially under conditions such as high temperature and/or RH where ambient NPF is unlikely to be observed? (2) What are the roles of amines and ammonia in particle formation and growth, particularly with regard to particle acidity? (3) How are growth rates in the 2-10 nm size range affected by the types of growth vapors present, especially condensing vs. partitioning organic species? (4) What is the role of isoprene in biogenic nucleation and growth ? does it suppress the NPF process? (5) What are the effects of photochemical and oxidation processes on biogenic NPF, especially the role of low vs. high NOx mixing ratios?