COLLABORATIVE RESEARCH: EFFECTS OF CHEMICAL AGING ON THE SURFACE VS. BULK COMPOSITION OF ATMOSPHERIC ORGANIC AEROSOL

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The Environmental Chemical Sciences Program in the Chemistry Division supports Professor Jesse H. Kroll of the Massachusetts Institute of Technology for the laboratory study of chemical differences between organic compounds present at the air-particle interface and those found within the bulk of the particles. New analytical techniques for the real-time measurement of the surface composition are being investigated and developed; these include combinations of soot particle aerosol mass spectrometry (SP-AMS, a laser-based technique for the rapid vaporization of particles containing black carbon or metal cores), tunable vacuum ultraviolet photoionization (VUV, a soft ionization technique), and direct analysis in real time (DART, a mass spectrometric technique for the measurement of material surfaces). These state-of-the-art techniques will then be used in environmental chamber studies, examining how the condensation of secondary species affect organic aerosol composition, with a focus on the extent and rate of mixing between various aerosol components. This study is expected to provide new insights into the formation and evolution of atmospheric organic fine particles. The direct examination of chemical gradients and mixing within such particles will provide important constraints on their atmospheric behavior, reactivity, and fate, and ultimately on their role in global climate and human health.