Fourier transform spectroscopy of the 13Δg-b3Πu transition in 6Li2

Abstract The 1 3 Δ g - b 3 Π u transition of 6 Li 2 has been observed in collisionally induced fluorescence following (a) excitation of the C 1 Π u state by the ultraviolet lines of argon and krypton ion lasers and (b) single frequency double resonance excitation of the F 1 Σ g + state using a ring dye laser operating with DCM dye. Spectra were obtained at high resolution using Fourier transform spectrometers. Many lines are broadened and shifted because of predissociation of b 3 Π u by a 3 Σ u + ; the widths and shifts have been measured as a function of rotation and vibration. Several perturbations have been observed in the 1 3 Δ g state and are shown to be caused by interaction with the 2 3 Π g state. The data are reduced to molecular constants (Dunham coefficients), perturbations are analyzed, and the collisional mechanism responsible for excitation of the 1 3 Δ g state is discussed.