Rotational analysis of the ground state and the lowest fundamentals nu(3),nu(5), and nu(6) of (CH3D)-C-13

The v(3), v(5), and v(6) fundamental bands of the (CH3D)-C-13 molecule have been studied with Fourier transform infrared spectroscopy. The spectra and results for the parent species (CH3D)-C-12 (O. N. Ulenikov, G. A. Onopenko , N. E. Tyabaeva, J. Schroderus, and S. Alanko, J. Mol. Spectrosc. 193, 249 -259 (1999)) have been used to assign and analyze about 1900 lines belongin g to the (CH3D)-C-13 isotopic species. About 850 ground state combination d ifferences with Delta K = O were calculated, which allowed us to determine the J-dependent ground state rotational constants. The K-dependent constant s as well as those describing the a(1)-a(2) (K = 3) splitting were fixed to the values obtained for the (CH3D)-C-12 species. The (v(3) = 1), (v(5) = 1 ), and (Vg = 1) states were fit simultaneously by including the intervibrat ional interactions in the Hamiltonian. The rotational energies, the rotatio nal and centrifugal distortion constants, as well as the resonance paramete rs involving the three states have been determined and discussed. (C) 2000 Academic Press.