Development of an Integrated System for Analyses of Aerosol Composition and Chemistry

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This Major Research Instrumentation (MRI) proposal is to develop a comprehensive laboratory system to characterize the composition and chemistry of aerosols. Three analytical subsystems will be assembled and integrated into a unique and powerful system for studying the composition, size distribution, and reactivity of aerosol particles believed to be important in the earth's atmosphere. Particles of controlled size and chemical composition will be generated with commonly used techniques such an atomizer and a fluidized bed nebulizer. The aerosols will be characterized by differential mobility analyzers and aerodynamic particle sizers and subsequently injected into a pressure- and temperature-controlled flow system similar to those employed for studies of highly reactive radicals and weakly bound species. In this reaction chamber the particles will be exposed to variable concentrations of gases like nitric acid, water vapor, inorganic acids, and organic compounds. The gas-phase composition of stable species (both reactants and products) will be monitored by tunable diode laser spectroscopy (TDLS), chemical ionization mass spectrometry (CIMS), and Fourier transform infrared spectroscopy (FTIR). The particle number and size distributions will be monitored in situ by optical scattering techniques. Finally, the particles will be focused through an aerodynamic inlet into a vacuum chamber where they will be sized by aerosol time-of-flight and their composition determined by mass spectrometry. The long-term goal of this project is to establish a multidisciplinary center for aerosol science which will foster close collaborations between investigators in universities, national laboratories, and industry.