Microwave Spectrum of 1,2-Difluoroethane

Butcher, Samuel S.; Cohen, Richard A.; Rounds, Thomas C.

doi:10.1063/1.1675477

Cited by 46 publications

(17 citation statements)

References 7 publications

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“…In the infrared analysis, the ground state constants are held fixed at the new microwave-determined values. Consistent with the prior microwave experiments (24,25), at the better than 10 kHz resolution of the microwave spectrometer no evidence was seen for splittings due to the tunneling between the two gauche conformers. The measured microwave transition frequencies are given in Table III and the spectroscopic constants determined from fitting the microwave transitions are given in Table IV.…”

Section: A 12-difluoroethanesupporting

confidence: 86%

“…The spectra are fit to the A-reduced Watson (23) asymmetrical-top Hamiltonian in the I r representation to near the measurement precision of 0.25 MHz. The high precision of the infrared measurements and high J states sampled in the infrared spectra required refinement of the previous ground state microwave constants (24,25), which was provided using the pulsed-nozzle Fourier-transform microwave spectrometer at NIST (26). In the infrared analysis, the ground state constants are held fixed at the new microwave-determined values.…”

Section: A 12-difluoroethanementioning

confidence: 99%

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Infrared Spectra of the 10-μm Bands of 1,2-Difluoroethane and 1,1,2-Trifluoroethane: Vibrationally Mediated Torsional Tunneling in 1,1,2-Trifluoroethane

Stone

Miller

Philips

et al. 1995

Journal of Molecular Spectroscopy

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Section: A 12-difluoroethanesupporting

confidence: 86%

Section: A 12-difluoroethanementioning

confidence: 99%

Infrared Spectra of the 10-μm Bands of 1,2-Difluoroethane and 1,1,2-Trifluoroethane: Vibrationally Mediated Torsional Tunneling in 1,1,2-Trifluoroethane

Stone

Miller

Philips

et al. 1995

Journal of Molecular Spectroscopy

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“…Table III. [42][43][44][46][47][48][49][50][51][52][53][54][55][56][57] It is shown that our calculations give very good results for the partially staggered conformation compared to the experimental values. For example, the calculated energy for the partially staggered conformation of CH 2 ICH 2 I is 2.54 kcal/ mol and the experimental value is 2.6 kcal/ mol.…”

Section: B the Rotational Potential Profile Of 12-substituted Haloesupporting

confidence: 55%

New torsion potential expression for molecules without rotational symmetry

Yan

Lü

2008

The Journal of Chemical Physics

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A new torsion potential function for bond rotations without rotational symmetry is proposed. This function is composed of a few Gaussian-type terms each corresponding to an eclipsed conformation of the 1,2 substituents of the C-C bonds. Different from the truncated Fourier series or the truncated cosine polynomial, it is easy to determine how many terms are needed to represent any type of torsion potential barrier at a glance using the Gaussian-type function. It could also intuitively deduce the physical meaning of the expansion parameters of the new torsion potential function, which corresponds to the barrier height, the dihedral defining the eclipsed conformations, and the size of the substituents, respectively. The new torsion potential function is also applied to the 1, 2-substituted haloethanes with satisfactory results, where three Gaussian-type terms corresponding to the fully eclipsed and the partially eclipsed conformations are needed.

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“…determined that the preferred conformation of 1,2‐difluoroethane in the gas phase was, in fact, gauche . This was contemporaneously substantiated by microwave spectroscopy, where a dihedral angle of Φ FCCF =73±4° was derived, and ultimately, by NMR coupling‐constant analysis and computation . The equilibrium dipole moment is also known for 1,2‐difluoroethane and shows an inverse temperature dependence (dμ/dT<0) .…”

Section: Introduction and Historical Overviewmentioning

confidence: 85%