ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The Fourier transform infrared spectrum of the in-plane CH3-rocking fundamental of 13CH3OH has been investigated at 0.002 cm−1 resolution. The rocking band is principally of parallel character and has a double-peaked Q branch and relatively wide spread subbands indicative of a substantial change in torsional barrier height. All A subbands from K=0 to 11 and all but one E subband from K=0 to 9 have been assigned in the n=0 torsional state and fitted to J(J+1) power-series expansions to obtain the subband origins and excited-state energy structure. The effects of vibrational interactions between the CH3-rocking and CO-stretching modes are prominent in the spectrum. Coriolis coupling between rocking (K−1) and CO-stretching K levels is observable for K≥6, and makes significant contributions to the subband origins and effective B values. Several J-localized perturbations due to level-crossing resonances with CO-stretch states have been observed and characterized. Two reported strong far-infrared laser lines optically pumped by the 10R(26) CO2 laser line have been found to arise through such a ΔK=3 level-crossing resonance. Modeling of the rocking-state torsion-K-rotation energies yields a height of V3r=469.2(38) cm−1 for the torsional potential barrier, a 26% increase over the ground state. The asymmetry K-doubling pattern in the excited state is qualitatively consistent with this barrier for K=2 to 4, but the K=5 rocking substate displays strongly enhanced splitting. © 1997 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.474530
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