Transient Intermediates in the Gas Phase

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Professor Frantisek Turecek, of the Department of Chemistry at the University of Washington, is supported by the Organic and Macromolecular Chemistry Program for his studies of the formation and properties of transient intermediates in chemical reactions in the gas phase. Molecules and radicals of sulfur oxyacids and nitroalkane radicals relevant to tropospheric oxidations, and intermediates in the addition of hydrogen atoms and hydroxyl radicals to nucleic bases, are generated by fast neutralization of cations and anions and studied by neutralization-reionization mass spectrometry. These studies, combined with complementary ab initio, density-functional theory, and RRKM calculations, address the stabilities of these transient intermediates in their ground and excited states and permit the analysis of their energetics and the kinetics of their unimolecular dissociation. Chemical reactions often proceed by consecutive elementary steps, each generating a transient and reactive intermediate. Characterization of such intermediates represents a formidable experimental challenge given their typically short lifetimes and low concentrations. An especially challenging class of transient intermediates to study is comprised of those formed by high-energy processes such as those that occur in the stratosphere and troposphere, in combustion, and in radiolysis by ionizing radiation. With the support of the Organic and Macromolecular Chemistry Program, Professor Frantisek Turecek, of the Department of Chemistry at the University of Washington, studies the formation and properties of transient intermediates in chemical reactions in the gas phase. Professor Turecek uses neutralization-reionization mass spectrometry, a `non-chemical` technique, for the production of the desired intermediates from simple precursor ions, avoiding the structural ambiguities which can result from their attempted production by other means. These studies, complemented by computational analyses, address the stabilities and reactivity of these transient intermediates, shedding light on the fundamental events which occur during high-energy processes.