INFRARED-MICROWAVE DOUBLE RESONANCE SPECTROSCOPY OF THE C-F STRETCHING FUNDAMENTAL AND TWO PERTURBING STATES OF 2-FLUOROETHANOL

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Title: INFRARED-MICROWAVE DOUBLE RESONANCE SPECTROSCOPY OF THE C-F STRETCHING FUNDAMENTAL AND TWO PERTURBING STATES OF 2-FLUOROETHANOL
Creators: Andrews, Anne M.; Pate, Brooks H.; Miller, C. Cameron; Philips, Laura A.; Fraser, G. T.
Issue Date: 1994
Publisher: Ohio State University
Abstract: Last year at this meeting we presented preliminary results on the C-F stretch of the $Gg^{\prime}$ conformer (the lowest energy of the five conformers) of 2-fluoroethanol at $1038 cm^{-1}$, which was observed using a microwave-sideband $CO_{2}$-laser electric-resonance optothermal $spectrometer.^{1}$ Only a fraction of the large number of transitions measured could be attributed to a single vibration. Further experiments have shown that transitions are present from two perturbing dark states in addition to the C-F stretch bright state. Microwave-infrared double resonance has been used to probe the microwave spectra of the dark states. The assignment of two complete additional bands accounts for all of the confirmed upper state energy levels and $ \cong 95%$ of the observed infrared transitions. The three bands are centered at 1039.26. 1040.93, and $1041.27 cm^{-1}$. Assuming the perturbers come from the same conformer, the dark state vibrations are tentatively assigned as the $\nu_{16}+\nu_{21}$ and the $\nu_{19}+5\nu_{21}$ combination bands. Due to the absence of a symmetry plane in this molecule, these levels can interact via anharmonic or parallel or perpendicular Coriolis coupling. For this reason, no attempt has been made to model the interaction. These measurements, combined with the results on the C-O stretch lead to a detailed characterization of the lowest frequency $\nu_{21}$ C-C torsional mode of 2-fluoroethanol. Knowledge of this vibration may permit greater understanding of the vibrational couplings in the higher frequency C-H stretching mode.
Description: $^{1}$. C.C. Miller, A. M. Andrews, G.T. Fraser, B.H. Pate and L.A. Philips, 48th Symposium on Molecular Spectroscopy, 1993.
Author Institution: Molecular Physics Division, National Institute of Standards and Technology; Department of Chemistry, University of Virginia; Department of Chemistry, Cornell University; Molecular Physics Division, National Institute of Standards and Technology
URI: http://hdl.handle.net/1811/13022
Other Identifiers: 1994-FC-13
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