The Fourier transform spectrum of the CH(3)(17)OH isotopologue of methanol has been recorded in the 65-1200 cm(-1) spectral region at a resolution of 0.00096 cm(-1) using synchrotron source radiation at the Canadian Light Source. Here we present an extension to higher torsional states of our investigation of the torsion-rotation transitions within the small-amplitude vibrational ground state, now including assignments of more than 16 500 lines involving quantum numbers in the ranges v(t) <= 3, J <= 30 and vertical bar K vertical bar <= 12, as well as a study of the strong CO-stretching band centered at 1020 cm(-1). Energy term values have been determined for assigned ground and CO-stretching levels by use of the Ritz program, and have been fitted to series expansions in powers of J(J + 1) to determine substate origins and effective B values. Several Fermi anharmonic and Coriolis level-crossing resonances coupling the CO stretch with high torsional ground-state levels have been identified and characterized. The study is motivated by astrophysical applications, with a principal aim being the compilation of an extensive set of energy term values to permit prediction of astronomically observable sub-millimetre transitions to within an uncertainty of a few MHz. (C) 2011 Elsevier Inc. All rights reserved.
Fourier transform synchrotron spectroscopy of torsional and CO-stretching bands of CH(3)(17)OH
MORUZZI, GIOVANNI;
2011-01-01
Abstract
The Fourier transform spectrum of the CH(3)(17)OH isotopologue of methanol has been recorded in the 65-1200 cm(-1) spectral region at a resolution of 0.00096 cm(-1) using synchrotron source radiation at the Canadian Light Source. Here we present an extension to higher torsional states of our investigation of the torsion-rotation transitions within the small-amplitude vibrational ground state, now including assignments of more than 16 500 lines involving quantum numbers in the ranges v(t) <= 3, J <= 30 and vertical bar K vertical bar <= 12, as well as a study of the strong CO-stretching band centered at 1020 cm(-1). Energy term values have been determined for assigned ground and CO-stretching levels by use of the Ritz program, and have been fitted to series expansions in powers of J(J + 1) to determine substate origins and effective B values. Several Fermi anharmonic and Coriolis level-crossing resonances coupling the CO stretch with high torsional ground-state levels have been identified and characterized. The study is motivated by astrophysical applications, with a principal aim being the compilation of an extensive set of energy term values to permit prediction of astronomically observable sub-millimetre transitions to within an uncertainty of a few MHz. (C) 2011 Elsevier Inc. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
