15min:

DENNIS J. CLOUTHIER AND SHENG-GUI HE, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055.

The A ² _u - X ² _g spectrum of the jet-cooled carbon disulfide cation (CS₂⁺) has been studied by laser-induced fluorescence and single vibronic level emission spectroscopic techniques. The ions were produced in a pulsed discharge jet using a precursor mixture of CS₂ vapor in argon. Analysis of the high-resolution spectrum of the ² _3/2 vibronic component of the 0-0 band has provided reliable ground and excited state molecular structures. A total of 33 LIF bands have been observed including a variety of hot bands from the µ ² and ² _5/2 vibronic components of the first bending level in the ground state. In emission, 34 ground state levels were observed, including all four components of v₂ = 1. The ground and excited state vibronic energy levels were fitted using a Renner-Teller model that included spin-orbit, vibrational anharmonicity, and Fermi resonance interactions. The spin-orbit splittings are much larger in the ground that in the excited state, although the Renner-Teller constants are comparable. The ₁ - 2 ₂ Fermi resonance interaction is very strong in both states and causes a nearly 50:50 mixing of the basis functions in each case.