Studies of Atmospheric Gas-to-Particle Conversion

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The atmospheric chemistry and gas-to-particle conversion phenomena of biogenic hydrocarbon systems will be investigated in this research project. The goals of the research are to elucidate the gas-phase photooxidation pathways of key biogenic hydrocarbons, to identify the aerosol-forming capability of these hydrocarbons, to further understanding of gas-to-particle conversion phenomena in atmospheric organic systems, and to evaluate the applicability of nucleation theories to atmospheric species. Outdoor smog chamber experiments will be conducted with isoprene/NOx and beta pinene/NOx mixture over a spectrum of concentration levels. Quantities to be measured include hydrocarbon, O3, NO, NO2 concentrations, aerosol size distributions by differential mobility analyzer, optical particle counter and epiphianiometer, and aerosol molecular composition by GC/MS and FTIR analyses. Aerosol species identified will be studied for nucleation either as single component or binary, with water. Theoretical work will continue on the development of a kinetic theory of nucleation. Analysis of the experimental data will involve a description of gas-phase chemical reaction mechanisms, including the generation of condensable species, the nucleation of these species, either homomolecular or binary, and the diffusion of these and additional species to particles.