FERMI MIXING AND FORBIDDEN TRANSITIONS IN METHANOL-$D_{1}$ AND CONFIRMATION OF OPTICALLY PUMPED FAR-INFRARED LASER LINES
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Date
1998
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Ohio State University
Abstract
This paper reports ``Forbidden'' transitions in the Fourier transform infrared (FTIR) spectrum, involving highly excited torsional levels within the ground vibrational state for $dK_{\rho} = 0, K_{\rho}= 4$ of methanol- $D_{1} (CH_{2}DOH)$ which become allowed through ``Fermi'' interaction with the OCD-bending vibrational state. This is the first time such transitions have been detected for any asymmetric- asymmetric molecule. The present findings represent a breakthrough in the assignment processfor asymmetrically substituted methanol, providing ample data for modeling of the Hamiltonian of the molecule. The findings are consistent with the far-infrared (FIR) laser lines pumped by $P(46) CO_{2}$ laser line of the 10.6 m band in $CH_{2}DOH$, which was earlier associated with an upshifted infrared (IR) transition but until now the mechanism of the anomalous shift remained a mystery. The results will be discussed in terms of the ``Fermi'' interaction and closed combination loops. Comments will be made on the internal rotational potential energy coefficients.
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Author Institution: Laser Programme, Centre for Advanced Technology