High-Resolution Near Infrared Spectroscopy and Vibrational Dynamics of Dideuteromethane (CH2D2)

We report the infrared spectrum of CH 2 D 2 measured in the range from 2800 to 6600 cm -1 with the Zurich high-resolution Fourier transform interferometer Bruker IFS 125 prototype (ZP 2001, with instrumental bandwidth less than 10 -3 cm -1 ) at 78 K in a collisional enclosive flow cooling cell used in the static mode. Precise experimental values (with uncertainties between 0.0001 and 0.001 cm -1 ) were obtained for the band centers by specific assignment of transitions to the J=0 level of 71 vibrational levels. In combination with 22 previously known band centers, these new results were used as the initial information for the determination of the harmonic frequencies, force constant parameters F ij , anharmonic coefficients, and vibrational resonance interaction parameters. A set of 47 fitted parameters for an effective Hamiltonian reproduces the vibrational level structure of the CH 2 D 2 molecule up to 6600 cm -1 with a root-mean-square deviation d rms = 0.67 cm -1 . The results are discussed in relation to the multidimensional potential hypersurface of methane and its vibrational dynamics.