THE CACCH A(2)PI-X-2-SIGMA(-RESOLUTION SPECTROSCOPY - THE CA-C-C BENDING VIBRATION AND VIBRONIC INTERACTION() 5(2)(2) AND 5(2)(0) BANDS STUDIED BY HIGH)

The CaCCH 5(2)(2) and 5(2)(0) bands in the (A) over tilde(2) Pi-(X) ov er tilde(2) Sigma(+) system, involving the excited Ca-C-C bending vibr ations, have been rotationally analyzed via CW dye laser excitation an d dispersed fluorescence with a CCD array detector. The (A) over tilde (2) Pi upsilon(5) = 2 level is subject to Renner-Teller and spin-orbit splittings; in addition, K-resonance interactions are observed betwee n the nearby (2) Phi and (2) Pi vibronic components. With a full matri x treatment of the six vibronic components (kappa(2) Pi, mu(2) Pi and (2) Phi) in the upper state, the line positions of the six subbands of the 5(2)(2) band were fitted simultaneously by least squares. The thr ee higher vibronic components, especially the kappa(2) Pi(1/2) compone nt, were found to be perturbed strongly by the lower vibronic componen ts of the upsilon(5)((2)) = 3 level. This perturbation has been analyz ed by means of second-order perturbation theory involving the (B) over tilde(2) Sigma(+) electronic state and results in an estimate of the dipolar vibronic interaction parameter, epsilon(5)((2))omega(5) = -8.3 1 cm(-1). The 5(2)(0) band was studied through dispersal fluorescence and served to establish an accurate energy of the upsilon(5) = 2 vibra tional level relative to the zero-point vibration level in both the (A ) over tilde and (X) over tilde states. (C) 1997 Academic Press.