High resolution infrared study of the a-axis

Abstract

Four fundamental bands in the infrared spectrum of 1,1-ethylene-d₂ have been studied at a resolution of ca. 0·05 cm^-1: the two type-B bands v ₆ and v ₁₀ and the two type-C bands v ₇ and v ₈. Analysis of a set of 409 ground state combination differences enables a complete set of ground state rotational and quartic distortion constants to be determined. The effect of the a-axis Coriolis interactions between the four bands is analysed, and upper state vibrational and rotational parameters for all four bands are obtained. Two localized higher order Coriolis perturbations are identified and characterized, and the band centre of the inactive twisting vibration v ₄ is estimated. From the overlapping and weak type-A band v ₃, a few upper state parameters are determined.