High resolution infrared and Raman spectra of (13)C(12)CD2: The CD stretching fundamentals and associated combination and hot bands

Infrared and Raman spectra of mono (13)C fully deuterated acetylene, (13)C(12)CD2, have been recorded and analysed to obtain detailed information on the C-D stretching fundamentals and associated combination, overtone, and hot bands. Infrared spectra were recorded at an instrumental resolution ranging between 0.006 and 0.01 cm(-1) in the region 1800-7800 cm(-1). Sixty new bands involving the \u3bd1 and \u3bd3 C-D stretching modes also associated with the \u3bd4 and \u3bd5 bending vibrations have been observed and analysed. In total, 5881 transitions have been assigned in the investigated spectral region. In addition, the Q branch of the \u3bd1 fundamental was recorded using inverse Raman spectroscopy, with an instrumental resolution of about 0.003 cm(-1). The transitions relative to each stretching mode, i.e., the fundamental band, its first overtone, and associated hot and combination bands involving bending states with \u3c54 + \u3c55 up to 2 were fitted simultaneously. The usual Hamiltonian appropriate to a linear molecule, including vibration and rotation l-type and the Darling-Dennison interaction between \u3c54 = 2 and \u3c55 = 2 levels associated with the stretching states, was adopted for the analysis. The standard deviation for each global fit is 640.0004\u2009cm(-1), of the same order of magnitude of the measurement precision. Slightly improved parameters for the bending and the \u3bd2 manifold have been also determined. Precise values of spectroscopic parameters deperturbed from the resonance interactions have been obtained. They provide quantitative information on the anharmonic character of the potential energy surface, which can be useful, in addition to those reported in the literature, for the determination of a general anharmonic force field for the molecule. Finally, the obtained values of the Darling-Dennison constants can be valuable for understanding energy flows between independent vibrations