FOURIER-TRANSFORM SPECTROSCOPY OF TORSIONALLY EXCITED C-13 METHANOL IN THE CO-STRETCHING BAND

Torsionally excited n=1 and n=2 subbands of the CO-stretching fundamen tal have been assigned in the Fourier transform infrared spectrum of ( CH3OH)-C-13 recorded at a resolution of 0.002 cm(-1). For the n=1 tors ional state, subbands with K values up to 7 have been identified for A torsional symmetry and up to 5 for E symmetry. For n=2, four subbands have so far been assigned. Subband origins have been obtained by fitt ing the observed wave numbers to J(J+-1) power-series expansions. The expansion parameters represent the data compactly to close to the expe rimental uncertainty in the absence of line blending or perturbations. Significant downshifting of the n=1 origins is observed, correlated c losely with proximity to the n=0 OH-bending state. J-localized perturb ations have been observed and characterized for several subbands. Two of the far-infrared laser lines optically pumped by the 10R(14) CO2 la ser line have been assigned. (C) 1996 American Institute of Physics.