title: The CaCCH A 2 Pi- X ; 2 Sigma+ 52 2 and 52 0 Bands Studied by High Resolution Spectroscopy: The Ca-C-C Bending Vibration and Vibronic Interaction
abstract: The CaCCH 52 2 and 52 0 bands in the A 2 Pi- X ; 2 Sigma+ system, involving the excited Ca-C-C bending vibrations, have been rotationally analyzed via CW dye laser excitation and dispersed fluorescence with a CCD array detector. The A 2 Pi v 5 = 2 level is subject to Renner-Teller and spin-orbit splittings; in addition, K -resonance interactions are observed between the nearby 2 Phi and 2 Pi vibronic components. With a full matrix treatment of the six vibronic components (kappa2 Pi, μ2 Pi, and 2 Phi) in the upper state, the line positions of the six subbands of the 52 2 band were fitted simultaneously by least squares. The three higher vibronic components, especially the kappa2 Pi1/2 component, were found to be perturbed strongly by the lower vibronic components of the v 5 = 3 level. This perturbation has been analyzed by means of second-order perturbation theory involving the B ; 2 Sigma+ electronic state and results in an estimate of the dipolar vibronic interaction parameter, epsilon5 (2) omega5 = -8.31 cm-1 . The 52 0 band was studied through dispersed fluorescence and served to establish an accurate energy of the v 5 = 2 vibrational level relative to the zero-point vibration level in both the A and X ; states.
authors.affiliation: Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, B3H 4J3, Canada
authors.initials: M
authors.lastname: Li
authors.initials: JA
authors.lastname: Coxon