15min:

ELISA MILLER, LEONID SHEPS, RYAN CALVI AND CARL LINEBERGER, JILA, Department of Chemistry, University of Colorado at Boulder, Boulder, Co 80309.

We report photoelectron spectra of IBr^-(CO₂)_n to understand the changes in IBr^- structure due to clustering. These experiments utilize anion photoelectron spectroscopy combined with velocity map imaging (VMI) to obtain photoelectron energy and angular distributions. Photodetachment of IBr^-(X^{2 +}) with 300 nm radiation accesses three neutral states of IBr: the ground state (X^{1 +}) and the next two excited states (³ ₂ and ³ ₁). Known excitation energies between the neutral states allow a direct calculation of the EA of IBr, 2.53 eV. Observed vibrational progressions resulting from transitions to the excited 3 states of IBr lead to equilibrium distances. Current experiments on IBr^-(CO₂)_n will be compared to that of the bare anion to understand changes in the structure of the cluster with additional CO₂ molecules.