THE MILLIMETER-WAVE AND SUBMILLIMETER-WAVE SPECTRUM OF (CH3OH)-C-13 REVISITED

The laboratory millimeter- and submillimeter-wave spectrum of the symmetric (A) and degenerate (E) substates of 13CH3OH has been extended to include 430 transitions in the A species and 411 transitions in the E species. For the A species, the observed transitions now include quantum numbers through J < 10 and K < 8 in the ground torsional state (vt = 0) and through J < 10 and K < 7 in the vt = 1,2 excited torsional states. For the E species, the observed transitions now include quantum numbers through J < 10 and |K| < 8 in the ground torsional state and through J < 10 and |K| < 6 in the vt = 1,2 excited torsional states. Modification of the extended internal axis method (IAM) Hamiltonian as in earlier work has reduced the overall root-mean-square deviation to the level of experimental accuracy. The new spectral constants derived from the nonlinear least-squares fit to the data have been used to predict the frequencies of an additional 562 transitions of 13CH3OH for vt = 0,1,2 and rotational quantum number J < 12.