Spectroscopic Investigations of Reactive Chemical Intermediates

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In this project supported by the Experimental Physical Chemistry Program of the Chemistry Division, Terry Miller of Ohio State University will use cavity ringdown spectroscopy (CRDS) and other techniques to investigate and characterize reactive chemical intermediates. Radical intermediates will be cooled using molecular-beam jets, and electronic transitions will be probed in the visible and infrared spectral regions. Calculations will be used to help analyze spectra, which then become a standard against which computational methods can be compared. Specific species to be examined include weakly bound clusters such as Ne2OH and Ne2SH, metal monomethyl radicals and larger alkyl derivatives, highly unsaturated carbon chain molecules, aryl carbenes, phenyl, and phenoxy radicals, alkyl peroxy radicals, and halogen dioxides.Complex chemical reactions that occur in atmospheric, combustion, and organic synthesis processes typically involve transient chemical intermediates, such as free radicals and molecular ions, that determine the overall result of the process. Spectroscopic identification of the intermediates is critical for the practical investigation and monitoring of such reactions. Spectroscopic characterization of the intermediates provides a foundation for the basic understanding of the nature of chemical reactivity. This research involves a multifaceted approach to the spectroscopic detection and characterization of these intermediates and species involving them. Such intermediates play critical roles in a variety of chemical reactions that are important in understanding such diverse phenomena as ozone depletion, lower-atmospheric air pollution, combustion, and astrochemistry.