# FOURIER TRANSFORM SPECTRA AND INVERTED TORSIONAL STRUCTURE FOR A $CH_{3}$-BENDING FUNDAMENTAL OF $CH_{3}OH$

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 Title: FOURIER TRANSFORM SPECTRA AND INVERTED TORSIONAL STRUCTURE FOR A $CH_{3}$-BENDING FUNDAMENTAL OF $CH_{3}OH$ Creators: Lees, R. M.; Xu, Li-Hong; Kristofferson, Anna K.; Lock, Michael; Winnewisser, B. P.; Johns, J. W. C. Issue Date: 2000 Publisher: Ohio State University Abstract: The high-resolution Fourier transform spectrum of $CH_{3}OH$ has been investigated in the $1400-1650 cm^{-1}$ region, containing the $CH_{3}$-bending fundamental bands. Twenty-two perpendicular $\Delta K=+1$ subbands have been identified so far, with origins ranging from 1490 to $1570 cm^{-1}$ for transitions $K=2 \leftarrow 1$ up to $11 \leftarrow 10$ for various torsional symmetries. Assignment of the subbands to the $\nu_{4}$ in-plane ($A^{\prime}$) or $\nu_{10}$ out-of-plane ($A^{\prime\prime}$) asymmetric methyl-bending modes is not yet clear, but the one subband so far observed with resolved K-doublet structure suggests c-type selection rules consistent with a $\nu_{10}$ vibrational assignment. The pattern of the $K$-reduced torsion-vibration energy $\tau$-curves is inverted compared to the normal 1- dimensional picture for $n = 0$ torsional levels, in agreement with prediction based on fitting torsional variation of ab initio $CH_{3}$-bending frequencies to a local mode model. However, the periodicity of the curves is unusual and significantly different from the ground state. The vibrational energy for the bending mode is $1481 cm^{-1}$, and the mean B-value is $0.008 cm^{-1}$ higher than that of the vibrational ground state. Description: Author Institution: Department of Physical Sciences, University of New Brunswick; Physikalisch-Chemisches lnstitut, Justus Liebig University; Steacie Institute for Molecular Sciences, National Research Council of Canada URI: http://hdl.handle.net/1811/19790 Other Identifiers: 2000-RG-11