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Rotational Spectrum and Internal Rotation Barrier of 1-Chloro-1,1-difluoroethane

✍ Scribed by José L. Alonso; Juan C. López; Susana Blanco; Antonio Guarnieri

Publisher
Elsevier Science
Year
1997
Tongue
English
Weight
815 KB
Volume
182
Category
Article
ISSN
0022-2852

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✦ Synopsis

The rotational spectra of 1-chloro-1,1-difluoroethane (HCFC-142b) has been investigated in the frequency region 8-115 GHz with Stark, waveguide Fourier transform (FTMW), and millimeter-wave spectrometers. Assignments in large frequency regions with the corresponding frequency measurements have been made for the ground and £ 18 Å 1 (CH 3 torsion) vibrational states of the 35 Cl isotopomer and for the ground state of the 37 Cl species. Accurate rotational, quartic centrifugal distortion, and quadrupole coupling constants have been determined from global fits considering all these states. Small A-E internal rotation splittings have been observed for the £ 18 Å 1 vibrational state using FTMW spectroscopy. The barrier height for the internal rotation of the methyl group has been determined to be 3751 (4) cal mol 01 , in disagreement with the previous microwave value of 4400 (100) cal mol 01 reported by G. Graner and C. Thomas [J.

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