The Analysis, Reactions and Growth of Aerosol Particles Studied by Vacuum UV Photoionization Mass Spectrometry

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Tomas Baer of the University of North Carolina at Chapel Hill is supported by The Experimental Physical Chemistry Program and the Atmospheric Chemistry Program to employ vacuum ultraviolet (VUV) light to investigate complex mixtures of organic constituents in aerosols generated in laboratory flow tubes, reaction chambers, and in an outdoor smog chamber. VUV light in the form of synchrotron radiation, pulsed laser-generated radiation, and rare gas resonance lamps will be utilized to study both large and small particles. The reactivity of model aerosols will be examined as a function of their morphology. The reaction rates of coated particles as well as particles consisting of organics embedded in porous particles with ozone will be measured in the laboratory. A major emphasis will be on identification of organic constituents in secondary organic aerosols and species generated by gas-particle reactions. A rare gas resonance lamp will be installed to investigate its use for detecting small particles in smog chamber studies that do not lend themselves to pulsed laser ionization. As well, experiments at the Advanced Light Source will be directed at controlled nucleation studies in a laboratory reaction chamber. Many naturally occurring small particles in the environment are highly heterogeneous, containing mixtures of carbon, salts, metals, and organic molecules. When these particles are in contact with certain gases, the chemical reactions that occur will be affected by the particle properties. New experimental methods to study aerosol particles will be developed in this project. In addition, the new methods will be used to examine aerosol formation in controlled atmospheres that mimic real-world environmental systems. This research will be carried out by students and postdoctoral associates, who will be broadly trained in physical, analytical, and environmental chemistry.