Microwave torsional-rotational spectra of gauche CH3CD2OH and CH3CD2OD

The microwave torsional-rotational spectra of gauche CH3CD3OH and CH3CD2OD have been identified, assigned, and analyzed up to 70 GHz. From the observed a- and c-dipole transitions, it has been possible to determine the effective rotational coefficients and the gauche tunneling energy of the hydroxyl internal rotation. The product of inertia terms I-xy and I-xz were included in the analyses using the framework fixed axis method (FFAM) approach to the hydroxyl internal rotation. Further, the analyses were sensitive to selected effective centrifugal distortion coefficients. For CH3CD2OH, a-dipole Lines were assigned for the first excited gauche state. As for CH3CH2OH, these lines were highly nonrigid rotor in behavior more than likely due to the resonance with the first excited state of the methyl torsion. (C) 2000 Academic Press.