Electronic and vibrational spectroscopy and vibrationally mediated photodissociation of V+(OCO)

Electronic spectra of gas-phase V+(OCO) are measured in the near-infrared from 6050 to 7420 cm(-1) and in the visible from 15500 to 16560 cm(-1), using photofragment spectroscopy. The near-IR band is complex, with a 107 cm(-1) progression in the metal-ligand stretch. The visible band shows clearly resolved vibrational progressions in the metal-ligand stretch and rock, and in the OCO bend, as observed by Brucat and coworkers. A vibrational hot band gives the metal-ligand stretch frequency in the ground electronic state v(3)" = 210 cm(-1). The OCO antisymmetric stretch frequency in the ground electronic state (v(1)") is measured by using vibrationally mediated photodissociation. An IR laser vibrationally excites ions to v(1)" = 1. Vibrationally excited ions selectively dissociate following absorption of a second, visible photon at the v(1)' = 1 <- v(1)" = 1 transition. Rotational structure in the resulting vibrational action spectrum confirms that VI(OCO) is linear and gives v(1)" = 2392.0 cm(-1). The OCO antisymmetric stretch frequency in the excited electronic state is v1' = 2368 cm(-1). Both show a blue shift from the value in free CO2, due to interaction with the metal. Larger blue shifts observed for complexes with fewer ligands agree with trends seen for larger V+(OCO)(n) clusters.