THE MICROWAVE SPECTRUM OF DICHLOROFLUOROMETHANE

1964 ◽  
Vol 42 (4) ◽  
pp. 720-730 ◽  
Author(s):  
David B. McLay
Keyword(s):  
Bond Length ◽  
Hyperfine Structure ◽  
Charge Distribution ◽  
Tensor Component ◽  
Microwave Spectrum ◽  
Frequency Range ◽  
Rotational Constants ◽  
Coupling Tensor ◽  
Quadrupole Coupling ◽  
Out Of Plane

The microwave spectra of C12HFCl235 and C12HFCl35Cl37 have been measured in the frequency range from 10 to 35 Gc/s. Enough R branch and Q branch rotational transitions have been measured in each case to determine the rotational constants A = 6988.73 ± 0.02, B = 3307.25 ± 0.05, and C = 2350.03 ± 0.02 Mc/s for CHFCl235 and A = 6943.37 ± 0.05, B = 3219.58 ± 0.04, and C = 2300.57 ± 0.06 Mc/s for CHFCl35Cl37. The out-of-plane coordinate of Cl35 in the symmetric species has been deduced to be 1.4350 ± 0.0006 Å and, if the C–Cl bond length is assumed to be 1.750 ± 0.005 Å, then the Cl–C–Cl angle can be calculated to be 112.2 ± 0.5°. The analysis of the hyperfine structure has led to the values eQVaa = −41.0 ± 0.2 Mc/s, eQVbb = +11.37 ± 0.13 Mc/s, and eQVcc = 29.62 ± 0.13 Mc/s for the diagonal components of the quadrupole coupling tensor along the principal inertial axes. The results are consistent with a cylindrically symmetrical charge distribution around the C–Cl bond and a quadrupole coupling tensor component of eQVzz = −76.75 Mc/s in the direction of the bond. The only impurity in the sample, obtained from the Matheson Company, seems to have been a trace of HCCF for which the J = 0 → 1 transition has been measured.

THE MICROWAVE SPECTRUM AND MOLECULAR STRUCTURE OF CHF2Cl

1962 ◽  
Vol 40 (1) ◽  
pp. 61-73 ◽  
Author(s):  
David B. McLay ◽  
C. R. Mann
Keyword(s):  
Bond Length ◽  
Electric Quadrupole ◽  
Microwave Spectrum ◽  
Molecular Structures ◽  
Moments Of Inertia ◽  
A Value ◽  
Principal Axes ◽  
Quadrupole Coupling ◽  
Out Of Plane ◽  
Tetrahedral Angle

Sufficient Q- and R-branch rotational transitions have been measured in the microwave spectrum of the asymmetric top molecule CHF2Cl to determine the moments of inertia Ia, Ib, and Ic for each of the three isotopic species C12HF2Cl35, C12HF2Cl37, and C13HF2Cl35. The value of Ia+Ic−Ib, which should depend only upon the out-of-plane co-ordinate of the fluorine atoms, is sufficiently constant to give a very accurate value for the co-ordinate of 1.08524 ± 0.00006 Å but involves some variations which limit the accuracy of determining molecular structures by isotopic substitutions. The components of the nuclear electric quadrupole coupling dyadics in the principal axes systems for the moments of inertia ellipsoids have been calculated accurately from the hyperfine structure of the C12HF2Cl35,37 spectra. In both cases, eQVaa+eQVbb+eQVcc = 0 and the ratio of any component for Cl35 to the same component for Cl37 is equal to 1.269 within the experimental error. The low-field Stark splitting of the 00,0 → 11,0 transition indicates a dipole moment component μc = 1.5 debyes while the absence of a-type transitions indicates a value for μa, which is less than 0.1 μc. The C—Cl bond length and the angle between this bond and the a-axis have been calculated by Kraitchman's formulae for isotopic substitution to be 1.747 ± 0.002 Å and 14.3 ± 0.2°. This angle and the values of eQVaa, eQVbb, and eQVcc lead to eQVzz = eQq = −71.5 ± 0.3 Mc/s and quadrupole coupling asymmetry parameter η = −0.012 ± 0.006, which indicates very little π-electron character. If the C—H bond length is assumed to be 1.095 ±.015 Å and the angle H—C—Cl is assumed to be 108 ± 1°, then the calculated values for the C—F bond length and for the angle F—C—F are 1.350 ±.003 Å and 107.0 ± 0.4°, a value considerably less than the tetrahedral angle. The values for bond lengths, bond angles, and nuclear electric quadrupole coupling components are compared with those in other halogenated methanes.

Das Rotationsspektrum des IBr / Rotational Spectrum of IBr

1975 ◽  
Vol 30 (8) ◽  
pp. 986-991 ◽  
Author(s):  
E. Tiemann ◽  
Th. Möller
Keyword(s):  
Hyperfine Structure ◽  
Rotational Transition ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Rotational Spectrum ◽  
Vibrational States ◽  
Hyperfine Parameters ◽  
Rotational Constants ◽  
Quadrupole Coupling

AbstractThe microwave spectrum of IBr was measured in the low rotational transition J = 3 ← 2 in order to resolve the hyperfine structure as completely as possible. Rotational constants and quadrupole coupling constants were derived for both nuclei. The observation of the rotational spectrum in different vibrational states yields the vibrational dependence of the rotational constants as well as of the hyperfine parameters. The Dunham potential coefficients a0, a1, a2, a3 are given.

Microwave Spectrum, Partial r0-Structure and 14N-Quadrupole Coupling Constants of 2-Cyanfurane

1976 ◽  
Vol 31 (6) ◽  
pp. 670-672 ◽  
Author(s):  
L. Engelbrecht ◽  
D. H. Sutter
Keyword(s):  
Nitrogen Atom ◽  
Electron Density ◽  
Cyano Group ◽  
Abundant Species ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Frequency Range ◽  
Rotational Constants ◽  
Quadrupole Coupling

The microwave spectrum of 2-Cyanfurane was investigated in the frequency range between 11 and 39 GHz. The rotational constants of the most abundant species indicate that the Cyano-group is bent toward the ring oxygen at the central C-atom. From the measured quadrupole coupling constants one may conclude that π-electron density is pulled from the ring toward the Nitrogen atom

The 33S Nuclear Quadrupole Coupling in the Rotational Spectrum of 2,2–Dimethylthiirane

1996 ◽  
Vol 51 (10-11) ◽  
pp. 1110-1112 ◽  
Author(s):  
Jens-Uwe Grabow ◽  
Masao Onda ◽  
Helmut Dreizler
Keyword(s):  
Hyperfine Structure ◽  
Coupling Constants ◽  
Rotational Spectrum ◽  
Rotational Constants ◽  
Its Analysis ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole

Abstract The rotational spectrum of 33S 2,2-dimethylthiirane with its 33S nuclear quadrupole coupling hyperfine structure in the range 8.9 to 20.0 GHz and its analysis is reported. The rotational constants are A = 5507.4663(3), B = 3440.58395(18), and C = 2978.5723(3) MHz. The 33 S quadrupole coupling constants are χaa = -22.6390(23), χbb = 47.1830(50), and χcc = -24.5440(50) MHz.

The Microwave Spectrum of 2,6-Lutidine, Analysis of Internal Rotation and 14 N Hyperfine Structure

1993 ◽  
Vol 48 (11) ◽  
pp. 1093-1101 ◽  
Author(s):  
C. Thomsen ◽  
H. Dreizler
Keyword(s):  
Fourier Transform ◽  
Hyperfine Structure ◽  
Internal Rotation ◽  
Molecular Beam ◽  
Microwave Spectrum ◽  
Methyl Groups ◽  
Rotational Spectrum ◽  
Rotational Constants ◽  
Moments Of Inertia ◽  
Nuclear Quadrupole

Abstract The rotational spectrum of 2,6-lutidine, (CH3)2C5H3N, has been recorded between 6 and 26.5 GHz using pulsed molecular beam microwave Fourier transform spectroscopy. The rotational constants are A = 3509.7139(84) MHz, B = 1906.8639(101) MHz, and C = 1254.6215(14) MHz, the barrier to internal rotation of the two methyl groups is V3 = 1.1752 kJ/mol, their moments of inertia were found to be Iα = 3.0808(9) uÅ2 . The nitrogen nuclear quadrupole constants are χaa = +1.600(5) MHz, χbb = -4.572(3) MHz and χcc = +2.972(5) MHz.

Nuclear Quadrupole Hyperfine Structure in the Rotational Spectrum of 3-Chloropyridine. An Application of Microwave-Microwave Double Resonance Fourier Transform Spectroscopy

1988 ◽  
Vol 43 (7) ◽  
pp. 657-661 ◽  
Author(s):  
N. Heineking ◽  
H. Dreizler
Keyword(s):  
Fourier Transform ◽  
Hyperfine Structure ◽  
Double Resonance ◽  
Fourier Transform Spectroscopy ◽  
Coupling Constants ◽  
Rotational Spectrum ◽  
Rotational Constants ◽  
Modulation Technique ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole

AbstractWe redetermined the rotational and the chlorine-35 and nitrogen-14 nuclear quadrupole coupling constants of 3-chloropyridine. The values are A = 5839.5330(12) MHz, B = 1604.1875(6) MHz, and C = 1258.3121 (5) MHz for the rotational constants, and χaa(Cl) = - 72.255(19) MHz, χbb(Cl) = + 38.500(13) MHz, χcc(Cl) = + 33.755(23) MHz and χaa(N) = - 0.009(13) MHz, χbb(N) = - 3.473(10) MHz, χCC(N) = + 3.482(16) MHz for the chlorine-35 and nitrogen-14 nuclear quadrupole coupling constants, respectively.Application of double resonance modulation technique is shown to greatly simplify the assign­ment of hyperfine structure components even of weak rotational transitions.

Microwave Spectrum of Acetyl Cyanide in the Ground and Excited States. I

1976 ◽  
Vol 31 (7) ◽  
pp. 840-846
Author(s):  
F. Scappini ◽  
H. Dreizler
Keyword(s):  
Internal Rotation ◽  
Excited States ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Rotational Constants ◽  
Microwave Spectra ◽  
Torsion Vibration ◽  
Quadrupole Coupling ◽  
Rotation Parameters

Abstract The microwave spectra of acetyl cyanide, CH3COCN, in the ground and in the two lowest excited states have been investigated. The rotational constants and the quadrupole coupling constants have been evaluated for all these states. The internal rotation parameters have been refined with respect to previous works. Evidence for a rotation-torsion -vibration interaction has been found in the spectra of the excited states.

14N Nuclear Quadrupole Hyperfine Structure in the Microwave Spectrum of Methyl Azide, CH3N3

1989 ◽  
Vol 44 (7) ◽  
pp. 669-674 ◽  
Author(s):  
N. Heineking ◽  
M.C.L. Gerry
Keyword(s):  
Hyperfine Structure ◽  
Ab Initio Calculation ◽  
Structural Information ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Rotational Spectra ◽  
Isotopic Species ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
First Time

Abstract The 14N nuclear quadrupole hyperfine structure in the rotational spectra of three isotopic species of methyl azide, CH3 14N3, CH3 15N14N2, and CH3 14N2 15N, has been resolved using microwave Fourier transform spectroscopy. The quadrupole coupling constants of 14N at all three positions have been evaluated and are compared with those from an ab initio calculation in the literature.Since the spectra of the substituted species have been obtained for the first time, they have provided new structural information: the rotational constants are consistent with a structure in which the NNN chain is slightly bent.

The Centimeter and Millimeter Microwave Spectrum of 1,1-Difluoro-2-Chloroethylene

1993 ◽  
Vol 48 (3) ◽  
pp. 514-518 ◽  
Author(s):  
Luis A. Leal ◽  
J. C. López ◽  
J. L. Alonso ◽  
A. Guarnieri
Keyword(s):  
Microwave Spectrum ◽  
Coupling Constants ◽  
Centrifugal Distortion ◽  
Frequency Range ◽  
Coupling Analysis ◽  
Rotational Spectra ◽  
First Order ◽  
Isotopic Species ◽  
Quadrupole Coupling ◽  
Centrifugal Distortion Constants

Abstract The rotational spectra of both 35Cl and 37Cl 1,1-difluoro-2-chloroethylene isotopomers have been measured in the frequency range 12-225 GHz. A first order quadrupole coupling analysis has been performed for both isotopic species. The calculated quadrupole coupling constants for the 37Cl species not previously reported are χaa = - 49.2 (2), χbb = 14.2 (1), and χcc = 28.7 (1). Accurate rotational constants, quartic and some sextic centrifugal distortion constants have also been determined for both isotopomers from the fit to the observed central frequencies.

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