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Title:Ftir synchrotron spectroscopy of the asymmetric C-H stretching bands of methyl mercaptan (CH3SH) – a perplexity of perturbations
Author(s):Lees, Ronald M.
Contributor(s):Billinghurst, Brant E.; Twagirayezu, Sylvestre; Perry, David S.; Dawadi, Mahesh B.; Thapaliya, Bishnu P.; Reid, Elias M.; Xu, Li-Hong
Subject(s):Spectroscopy of Large Amplitude Motions
Abstract:The infrared Fourier transform spectrum of the asymmetric C-H stretching bands of CH$_{3}$SH has been recorded in the 2950-3100 cm$^{-1}$ region at Doppler limited resolution using synchrotron radiation at the FIR beamline of the Canadian Light Source in Saskatoon. Assignment of numerous torsion-rotation sub-bands for the asymmetric stretches has revealed a surprising pseudo-symmetric behavior, in which each band is seen in only one of the two possible $\Delta$K selection rules. The upper states of the two asymmetric stretching vibrational bands thus appear to behave more like $\it{l}$ = $\pm$ 1 components of a degenerate E state of a symmetric top rather than distinct vibrational states. The two components are separated by about 1.5 cm$^{-1}$ at K = 0, and then diverge linearly at higher K with torsional oscillation amplitude similar to that of the ground state of about 1.3 cm$^{-1}$. The divergence is consistent with an a-type Coriolis splitting picture with an effective Coriolis constant $\zeta$ $\approx$ 0.075.
Issue Date:2016-06-21
Publisher:International Symposium on Molecular Spectroscopy
Genre:Conference Paper/Presentation
Rights Information:Copyright 2016 by the authors
Date Available in IDEALS:2016-08-22

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