Investigation of the Torsion Rotation Energy Levels of the CH3 Asymmetric Stretches in Methanol

✍ Scribed by O.N. Bignall; R.H. Hunt; W.N. Shelton

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 546 KB
• Volume: 166
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.1994.1179

✦ Synopsis

The (\mathrm{CH}{3}) asymmetric stretching region of methanol vapor has been investigated between 2900 and (3200 \mathrm{~cm}^{-1}) with a (1.25-\mathrm{m}) maximum path difference Fourier transform spectrometer. Thirteen (P) branches and eleven (R) branches were assigned ( 13 series representing six excited states belonging to the (\nu{2}) fundamental and 11 series representing five excited states belonging to the (\nu_{9}) fundamental ). A nonlinear least-squares analysis of the (Q)-branch origins for three parameters (the bandcenter, the hindering potential barrier height, and the moment of inertia of the methyl group about the symmetry axis) of the molecule was done. This yielded a bandcenter of (2999.44 \mathrm{~cm}^{-1}), a barrier height of (405.62 \mathrm{~cm}^{-1}), and a moment of inertia of (5.29 \mathrm{~cm}^{-1}) for the (\nu_{2}) fundamental. The corresponding values for the (\nu_{9}) fundamental are (2970.18,529.71), and (5.34 \mathrm{~cm}^{-1}), respectively. The ambiguity of these parameters owing to the relatively small number of identified torsional levels is discussed. 1994 Academic Press, Inc.