Real-Time Characterization of Airborne Macromolecules

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Professor Murray Johnston of the University of Delaware is supported by the Analytical and Surface Chemistry Program in the Division of Chemistry and by Atmospheric Sciences in the Directorate for Geosciences to develop an ion trap - time of flight mass spectrometer for real-time characterization of macromolecules in airborne particles. Both matrix-assisted laser-desorption ionization and chemical ionization will be used. At present, there is no suitable method for real-time detection and quantification of these species, making it difficult to study their formation and reactivity in either laboratory reactors or in the atmosphere. The analytical methodology developed in this work will be used to study the factors that control the polymerization reactions of lower molecular weight precursors in secondary organic aerosol (SOA). The chemical composition of SOA, its relative contribution to carbonaceous fine particulate matter, and its ultimate environmental impact will be investigated. Graduate and undergraduate students will be educated in this interdisciplinary research area involving chemistry and atmospheric sciences. This project will provide answers to critical questions about global climate. Current atmospheric models do not account for polymerization. As a consequence, it is likely that current global estimates of SOA are too low, and the effect of SOA on global climate is underestimated. The methodology is also relevant to bioaerosol characterization for homeland security applications.