THE MICROWAVE SPECTRUM OF THE $CH_{3}OH-CO$ DIMER
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Date
1993
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Publisher
Ohio State University
Abstract
The rotational spectrum of $CH_{3}OH-CO$ has been observed in the 7-18 GHz region with a pulsed beam Fabry-Perot cavity Fourier transform microwave spectrometer. The measurement precision and accuracy is estimated to be 4 kHz. In order to obtain detailed structural information the spectra of $CH_{3}OH, CH_{3}OD, CD_{3}OH$ and $CD_{3}OD$ complexed with $^{12}CO$ and $^{13}CO$ were examined. Each of the isotopic species exhibits two states which are interpreted as A and E symmetry states arising from internal rotation of the methyl group. The E-state assignments were verified by observing their first-order Stark effect. The spectra were analyzed using the IAM method. Only a small change in the value of the barrier to the internal rotation was found for the different species, suggesting that a possible second large-amplitude motion (overall rotation of the CO subunit) can be neglected at the present stage of the experimental data set. The structure of the complex involves planar heavy atoms and a bent hydrogen bond to the carbon atom of CO at a distance of 2.43 A from the hydroxyl hydrogen of methanol.
Description
Author Institution: Molecular Physics Division, National Institute of Standards and Technology; Microwave Spectroscopy Division, Applied Physics Institute