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.

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.

NUCLEAR ELECTRIC QUADRUPOLE INTERACTION IN SINGLE CRYSTALS

1952 ◽  
Vol 30 (3) ◽  
pp. 270-289 ◽  
Author(s):  
G. M. Volkoff ◽  
H. E. Petch ◽  
D. W. L. Smellie
Keyword(s):  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Electric Quadrupole ◽  
Quadrupole Coupling Constant ◽  
Coupling Constant ◽  
Gradient Tensor ◽  
Absolute Value ◽  
Principal Axes ◽  
Quadrupole Coupling

Pound's theory of the dependence of electric quadrupole splitting of nuclear magnetic resonance absorption lines in a single crystal on the orientation of the crystal in an external magnetic field is extended to cover the case of a crystal with nonaxially symmetric electric field gradient at the site of the nuclei being investigated. It is shown that an experimental study of the angular dependence of this splitting for three independent rotations of the crystal about any three mutually perpendicular axes will yield complete information about the orientation of the principal axes and the degree of axial asymmetry of the electric field gradient tensor at the site of the nuclei, and also will give the absolute value of the quadrupole coupling constant for those nuclei.The authors' experiments on the splitting of the Li7 absorption lines in a single crystal of LiAl(SiO3)2 (spodumene) are described and are used to illustrate the theory. The absolute value of the quadrupole coupling constant for the Li7 nuclei in spodumene is found to be [Formula: see text]. per sec. The axial asymmetry parameter of the field gradient tensor at the site of the Li nuclei is found to be η≡(ϕxx−ϕvv)ϕzz=0.79 ± 0.01. One of the principal axes of this tensor (the y axis corresponding to the eigenvalue of intermediate magnitude) is experimentally found to coincide with the b crystallographic axis of monoclinic spodumene as required by the known symmetry of the crystal. The other two principal axes are in the ac plane, the z axis (corresponding to the eigenvalue ϕzz of greatest magnitude) lying between the a and c axes at an angle of 48° ± 2° with the c axis.

The shape of the Moon, its internal structure and moments of inertia

1967 ◽  
Vol 296 (1446) ◽  
pp. 254-265 ◽  
Keyword(s):  
Convective Motion ◽  
The Moon ◽  
Moments Of Inertia ◽  
Lunar Interior ◽  
A Value ◽  
Principal Axes ◽  
Thermoelastic Effects ◽  
The Mean ◽  
The Stability ◽  
Sufficient Strength

Harmonic analysis of the Moon’s shape based on all available sets of hypsometric data disclose that the surface of the Moon, far from being a mere spheroid or ellipsoid, contains many significant harmonic terms, the single largest of which are of fourth order (being about three times as large as the second harmonics). Their sum makes the Moon to deviate from a mean sphere by ± 2 km over extensive regions; and local differences attaining 8 to 9 km in eleva­tion have been noted on the limb. These facts reveal that the lunar globe must possess sufficient strength to sustain stress differences of the order of 10 9 dyn/cm 2 ; and this could scarcely be the case if the large part of the Moon’s interior were molten. As melting should be expected if the Moon contained the same proportion of radioactive elements as chondritic meteroites, it is concluded that the mean radioactive content of the lunar interior must be less than that found in stony meteorites, or the terrestrial crust. The moments of inertia about the principal axes of inertia of the lunar globe, as determined from the Moon’s physical librations, are seriously at variance with a state of hydrostatic equilibrium—for any distance between the Earth and the Moon—of a homogeneous body, and can be accounted for only by assuming an asymmetric nonhomogeneity of the lunar globe, or the existence of internal processes which could support nonequilibrium from hydrodynamically. However, an application of Chandrasekhar’s theory of viscous convection in fluid globes reveals that, if such a globe is to possess the same difference, C – A , of momenta as the Moon, the velocity of convective motion should be of the order of 10 –8 cm/s (i. e. too small for the establishment of steady flow in 10 9 y); and the 'observed' value of the Rayleigh number characteristic of the Moon is several hundred times as large as that required theoretically for the stability of the respective flow. Thermoelastic effects due to secular insolation of the lunar globe, considered recently by Levin, are shown incapable to account for a value of the ratio (C – A)/B exceeding 0∙00005; while its empirical value deduced from librations is close to 0∙00063.

Microwave spectrum of morpholine

1969 ◽  
Vol 47 (18) ◽  
pp. 3453-3462 ◽  
Author(s):  
J. J. Sloan ◽  
R. Kewley
Keyword(s):  
Dipole Moment ◽  
Vibrational State ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Chair Conformer ◽  
Imino Group ◽  
Ground Vibrational State ◽  
Principal Axes ◽  
Quadrupole Coupling ◽  
Equatorial Conformer

The microwave spectra of morpholine and N-deuteromorpholine have been investigated within the 8 to 40 GHz region. For both the normal and the deuterated species, strong a-type spectra which are due to the chair conformer with an equatorial imino group were recorded. The ground vibrational state rotational constants and quadrupole coupling constants are (in MHz), for normal morpholine, A = 4924.88 ± 0.05, B = 4625.15 ± 0.05, C = 2684.25 ± 0.05, χaa = 2.22 ± 0.02, χbb = 2.51 ± 0.04, χcc = −4.73 ± 0.02, and for N-deuteromorpholine, A = 4925.39 ± 0.05, B = 4399.67 ± 0.05, C = 2607.09 ± 0.05, χaa = 1.92 ± 0.02, χbb = 2.59 ± 0.04, χcc = −4.51 ± 0.02. The rs coordinates of the imino hydrogen are (in Å) aH = 2.373 ± 0.005 and cH = 0.10 ± 0.03. For the normal species the dipole moment components are (in D) μa = 1.68 ± 0.01, μc = 0.30 ± 0.01, μ = 1.71 ± 0.02. The value of aH and the direction of μ with respect to the a and c principal axes confirm that the observed spectrum is that of the chair equatorial conformer of morpholine.

Experimental Study of Nuclear Electric Quadrupole Splittings of 59Co in Co(NH3)6Cl3

1974 ◽  
Vol 52 (15) ◽  
pp. 1398-1404 ◽  
Author(s):  
E. C. Reynhardt
Keyword(s):  
Experimental Study ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Electric Field Gradient ◽  
Room Temperature ◽  
Electric Quadrupole ◽  
Coupling Constants ◽  
Principal Axes ◽  
Quadrupole Coupling ◽  
Asymmetry Parameters

The nuclear magnetic resonance of 59Co in a single crystal of Co(NH3)6Cl3 has been investigated at room temperature at 15 kG. Observed quadrupolar perturbations have been analyzed by the method of Volkoff for three orthogonal planes to yield five electric field gradient tensors. The cobalt sites associated with these tensors are nonequivalent. The quadrupole coupling constants and asymmetry parameters vary from 1.0 to 17.2 MHz and 0.10 to 0.57 respectively. One of the principal axes of each tensor is found to coincide with the crystallographic b axis of the monoclinic unit cell.

Investigation of the Microwave Spectrum of cis-Cyclopropyl Carbonyl Chloride-(35Cl); Determination of the Quadrupole Coupling Tensor in its Principal Axes System

1990 ◽  
Vol 45 (9-10) ◽  
pp. 1169-1174 ◽  
Author(s):  
C. Heldmann ◽  
H. Dreizler ◽  
R. Schwarz
Keyword(s):  
Diagonal Element ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Centrifugal Distortion ◽  
Coupling Tensor ◽  
Principal Axes ◽  
Quadrupole Coupling ◽  
Carbonyl Chloride ◽  
Centrifugal Distortion Constants

Abstract The vibrational ground state microwave spectrum of cis-cyclopropyl carbonyl chloride-(35Cl) was investigated in the region from 4 to 40 GHz by microwave Fourier transform (MWFT) spectroscopy. The rotational and fourth order centrifugal distortion constants were determined. The quadrupole hyperfine structure was assigned and the quadrupole coupling constants including the off-diagonal element i ab were evaluated. This leads to a transformation of the quadrupole coupling tensor into its principal axes system.

scholarly journals Microwave Spectrum and Quadrupole Coupling Constants of 2-Chlorothiophene

1973 ◽  
Vol 28 (5) ◽  
pp. 729-738 ◽  
Author(s):  
J. Mjöberg ◽  
S. Ljunggren
Keyword(s):  
Ground State ◽  
Hyperfine Splitting ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Centrifugal Distortion ◽  
Vibrationally Excited ◽  
Isotopic Species ◽  
Principal Axes ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole

The microwave spectra of the two chlorine isotopic species of 2-chlorothiophene have been measured in the region 26 500 - 40 000 MHz.For both isotopic species, the rotational constants of the ground state and one vibrationally excited state were determined, as well as the centrifugal distortion coefficients of the ground state.From the hyperfine splitting of the rotational lines, the nuclear quadrupole coupling constants were calculated. The values in MHz are for 35Cl:and for 37Cl: χaa= -74.77 ±0.05, χbb=37.51 ± 0.17, χcc=37.25 ± 0.18 χaa= -58.98 ±0.09, χbb=29.55 ± 0.26, χcc=29.43 ± 0.28in the principal-axes system of the molecule.

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