Knowledge Bank

The infrared high-resolution Fourier transform spectrum of O-17 methanol has been recorded and investigated in the region from 960 to $1060cm-1$ at $0.002cm-1$ resolution. The CO-stretching fundamental band is centered at $1020cm-1$ and has the structure of a parallel band with well-defined J-multiplets. For the ground torsional state we have identified 28 subbands for K values from 0 to 9 for the three torsional symmetries. The assignments are supported by combination differences derived from calculated a-type ground-state wavenumbers. Fermi shifts due to resonances between CO-stretch and torsionally-excited ground-state levels at the level-crossing points for states with the same torsional symmetry have been observed in the spectrum. The assigned subbands have been fitted as J(J + l) power-series expansions in order to determine the infrared subband origins and state-specific constants describing the J-dependence of the subbands. A least squares fit of the IR band origins, with ground-state molecular constants held fixed, indicates that the CO-stretch barrier height is slightly higher than the ground-state value. Several predictions for optically-pumped far-infrared laser lines are proposed from our spectroscopic results, with IR pumping in the CO-stretch band.