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SAMANTHA HORVATH, ANNE B. MCCOY AND RUSSELL M. PITZER, Department of Chemistry, The Ohio State University, Columbus, OH 43210.

In the present study, we examine the time-resolved photoelectron spectra of IBr^-. In the photodetachment studies performed by Sanov and co-workers and Lineberger and co-workers,\footnoteR. Mabbs, K. Pichugin, and A. Sanov, J. Chem. Phys. , 2005, 122 , 174305; Leonid Sheps, Elisa M. Miller, and W. C. Lineberger (private communication). the anionic species, prepared in its electronic ground state (² _1/2⁺), is excited to either its A ' (² _3/2) or B (² _1/2⁺) excited state, before electron photodetachment and dissociation on the C (¹ ₁) or higher-lying excited states of the neutral species, respectively. In this work, we use the electronic structure program Columbus to calculate the six lowest electronic states of IBr^- and the ten lowest states of IBr at the MR-SO-CISD/aug-cc-pVDZ level of theory/basis, using relativistic core potentials for I and Br. Experimentally determined electronic states of IBr are also used.\footnoteE. Wrede, S. Laubach, S. Schulenburg, A. Brown, E. R. Wouters, A. J. Orr-Ewing, and M. N. R. Ashfold, J. Chem. Phys. , 2001, 114 (6), 2629. Vibrational eigenstates for these electronic states are calculated in a discrete variable representation,\footnoteD. T. Colbert and W. H. Miller, J. Chem. Phys. , 1992, 96 (3), 1982. and propagation of the thermally populated X -state vibrational wave functions on either the A ' or B electronic states of the anion is performed using a Lanczos scheme. We then take time-dependent overlaps between these propagated states and the vibrational eigenstates of the neutral surface. Results for IBr^- show good agreement with the experimental time-resolved spectra. Extensions to IBr^-(CO₂)_n (n < 2) will also be discussed.