HIGH-RESOLUTION INFRARED SPECTRA OF THE METHYL C-H-VIBRATIONS IN ETHYL RADICAL
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Date
2003
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Ohio State University
Abstract
All three CH-stretch vibrations of the methyl group in ethyl radical have been measured using high-resolution infrared spectroscopy in a slit supersonic discharge expansion source. Rotational assignment and analysis has been performed on each of these spectra providing rotational and centrifugal-distortion constants. We see one A-type band, which corresponds nominally to the symmetric stretch vibration, with a band origin at $2854.1027(3) cm^{-1}$. Instead of a nominally degenerate vibration, the methyl asymmetric CH stretch is split into two B- and C-type bands with a separation of $124.5361 cm^{-1}$ due to internal rotation around the C-C bond. When compared to the splitting in $nitromethane,^{ab}$ an analogous model system for hindered internal rotation, this separation is substantially larger.
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$^{a}$D. C. McKean and R. A. Watt, J. Mol. Spectrosc. 61, 184 (1976) $^{b}$D. Gorse, D. Cavagnat, M. Pesquer, and C. Lapouge, J. Phys. Chem. 97, 4262 (1993)
Author Institution: JILA, University of Colorado
Author Institution: JILA, University of Colorado