ELECTRONIC PHOTODISSOCIATION SPECTROSCOPY OF GAS-PHASE IrBr$_n^{k-}$

Author Institution: JILA, NIST, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309Iridium complex anions (IrBr$_6^{2-}$, IrBr$_5^-$ and IrBr$_4^-$) were studied using photodissociation spectroscopy in the photon energy range between 1.1 and 5.6 eV. These spectra probe the electronic structure of iridium bromide complexes as a function of the coordination number and metal oxidation state. The observed spectra for isolated IrBr$_6^{2-}$ contain similar features to its spectrum in aqueous solution. An analysis of the fragment channels reveals a tendency for formation of IrBr$_5^-$ fragment ions in the visible while formation of IrBr$_4^-$ fragment ions is favored in the ultraviolet. Spectra for IrBr$_5^-$ and IrBr$_4^-$ parent ions indicate that their preferred fragment channel is the loss of one or more neutral bromine atoms