Speaker
Dr
Li-Hong Xu
(Physics Dept., University of NB)
Description
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 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 $l$ = $\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.
Primary author
Dr
Li-Hong Xu
(Physics Dept., University of NB)
Co-authors
Mr
Bishnu P. Thapaliya
(Dept. of Chemistry, University of Akron)
Dr
Brant E. Billinghurst
(Canadian Light Source, University of Saskatchewan)
Dr
David S. Perry
(Dept. of Chemistry, University of Akron)
Mr
Elias M. Reid
(Physics Dept., University of NB)
Dr
Mahesh B. Dawadi
(Dept. of Chemistry, University of Akron)
Dr
Ronald M. Lees
(Physics Dept., University of NB)
Dr
Sylvestre Twagireyazu
(Dept. of Chemistry, Brookhaven National Laboratory, Upton, NY)
