Gas Phase Ion Chemistry and Thermochemistry

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

In this proposal funded by the Experimental Physical Chemistry Program of the Chemistry Division, Veronica Bierbaum of the University of Colorado will pursue a program of research on the kinetics, mechanisms, and thermochemistry of gas phase ion-molecule reactions. Tandem flowing afterglow-selected ion flow tube instruments will be used to study the gas-phase ion thermochemistry of peroxyls, hexamethylene tetramine, nobornadiene, and pentalene. Nucleophilic substitution and elimination reactions, their competition, solvation effects, and solvent kinetic isotope effects will be examined. Reactions of nitrogen and oxygen with many different ions will be investigated, with special emphasis on anion chemistry, novel product ions, and isotope exchange. Negative and positive chemical ionization techniques for volatile organic detection will be extended to studying rate constants, branching ratios, H/D exchange and CID fragmentation patterns. Much of the thermochemical data gathered in this program has relevance to important combustion and atmospheric processes. The sources of high concentrations of oxygenated hydrocarbons in the earth's troposphere are not currently understood, but their impact on atmospheric chemistry is significant. The characterization of biogenic emissions from a variety of growing and harvested plants addresses this critical problem in atmospheric chemistry. The experimental results from this research will also contribute to the fundamental understanding of reaction kinetics and thermochemistry and will provide valuable intercomparison with theory.