FIR SYNCHROTRON SPECTROSCOPY OF HIGH TORSIONAL LEVELS OF CD3OH: THE TAU OF METHANOL

Lees, Ronald M.

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https://hdl.handle.net/2142/79167 Copy

Description

Title

FIR SYNCHROTRON SPECTROSCOPY OF HIGH TORSIONAL LEVELS OF CD3OH: THE TAU OF METHANOL

Author(s)

Lees, Ronald M.

Contributor(s)

• Billinghurst, Brant E.
• Xu, Li-Hong

Issue Date

23-Jun-15

Keyword(s)

Mini-symposium: Accelerator-Based Spectroscopy

Abstract

Sub-bands involving high torsional levels of the CD$_3$OH isotopologue of methanol have been analyzed in Fourier transform spectra recorded at the Far-Infrared beamline of the Canadian Light Source synchrotron in Saskatoon. Energy term values for $A$ and $E$ torsional species of the third excited torsional state, v$_t$ = 3, are now almost complete up to rotational levels $K$ = 15, and thirteen substates have so far been identified for v$_t$ = 4. The spectra show interesting close groupings of high-v$_t$ sub-bands related by Dennison�s torsional symmetry label $tau$, rather than $A$ and $E$, that can be understood in terms of a simple and universal free-rotor �spectral predictor� chart. Transitions between states on the same free rotor curve have torsional overlap matrix elements close to unity, so give rise to strong sub-bands providing radiative routes for rapid population transfer through the high torsional manifold. Where the energy curves for the v$_t$ = 3 and 4 ground-state torsional levels pass through the excited vibrational states, strong resonances can occur and a number of anharmonic and Coriolis interactions have been detected through perturbations to the spectra and appearance of forbidden transitions due to strong mixing and intensity borrowing.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

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http://hdl.handle.net/2142/79167

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