Our research is directed towards understanding how molecules react and the factors that determine the rates and products of chemical reactions. The principal areas of research involve the spectroscopy, photochemistry, reaction dynamics, and reaction mechanisms of ions in the gas phase.
The primary experimental technique used in our research is Ion Cyclotron Resonance (ICR) spectroscopy. We have assembled continuous wave, pulsed, and Fourier-transform instruments. These are coupled with a variety of light sources, including conventional arc lamp/monochromator, argon ion/dye laser/Ti-Sapphire laser, cw CO2 infrared laser, and pulsed TEA CO2 infrared lasers.
Among our current projects are attempts to understand the basis of gas-phase ion reaction dynamics. In particular, we are developing statistical and other models for reaction rates. We make use of the analysis of potential surfaces, for example, to define and characterize nucleophilicity in negative ion reactions without solvent. We are attempting to understand the nature of steric effects and hydrogen bonding and the effects of solvent on these phenomena. We make use of multiple photon infrared absorption to activate reactants or possible intermediates in reactions and observe their unimolecular decomposition.
Finally, we use visible photons to effect detachment of electrons from negative ions. By studying the details of the electron photodetachment process (onsets, threshold shapes, resonances, fine structure, etc.) we learn about electron affinities, electronic structure in ions, excited electronic states in ions, and vibrational structure and spin orbit splitting (or triplet-singlet splitting) in the final state neutrals.
1) "Direct Observation of Spin Forbidden Proton Transfer Reactions: 3NO- + HA ->1HNO + A-," G.A. Janaway and J.I. Brauman, J. Phys. Chem. A, 104, 1795-1798 (2000).
2) "Hydrogen Bonded Complexes of Methanol and Acetylides. Structure and Energy Correlations," M.L. Chabinyc and J.I. Brauman, J. Am. Chem. Soc., 122, 5371-5378 (2000).
3) "Intramolecular Microsolvation of SN2 Transition States," S.L. Craig and J.I. Brauman, J. Am. Chem. Soc., 121, 6690-6699 (1999).
4) "Translational Energy Dependence and Potential Energy Surfaces of Gas Phase SN2 and Addition-Elimination Reactions," S.L. Craig, M. Zhong, and J.I. Brauman, J. Am. Chem. Soc., 121, 11790-11797 (1999).
5) "Acidity, Basicity, and the Stability of Hydrogen Bonds: Complexes of RO- + HCF3," M.L. Chabinyc and J.I. Brauman, J. Am. Chem. Soc., 120, 10863-10870 (1998).
6) "Gas-Phase Ionic Reactions: Dynamics and Mechanism of Nucleophilic Displacements," M.L. Chabinyc, S.L. Craig, C.K. Regan, and J.I. Brauman, Science, 279, 1882-1886 (1998).
7) "Electron Photodetachment Spectroscopy of (E)- and (Z)-Propionaldehyde Enolate Anions. Electron Affinities of the Stereoisomers of Propionaldehyde Enolate Radicals," B.C. RÃ¶mer and J.I. Brauman, J. Am. Chem. Soc., 119, 2054-2055 (1997).
8) "Perturbed Equilibria and Statistical Energy Redistribution in a Gas Phase SN2 Reaction," S.L. Craig and J.I. Brauman, Science, 276, 1536-1538 (1997).
9) "Molecular Rotation and the Observation of Dipole-Bound States of Anions," E.A. Brinkman, S. Berger, J. Marks, and J.I. Brauman, J. Chem. Phys., 99, 7586-7594 (1993).