Nuclear quadrupole coupling constants spectrum

All the NMR interaction parameters for zinc metal have been determined from the central and satellite transitions of the Zn spectrum which indicates a value of — 124 ppm for the axial component of the Knight shift. The isotropic component of the Knight shift and the nuclear quadrupole coupling constant have also been determined as a funtion of temperature over the range 149 32 K (Bastow 1996). 

Soper, P.D., Fegon, A.C., Read, W.G., and Flygare, W.H. (1982) The microwave rotational spectrum, molecular geometry,14N nuclear quadrupole coupling constants, and H-1S>F nuclear spin-nuclear spin coupling constant of the nitrogen-hydrogen fluoride dimer. J. Chem. Phys., 76, 292-300. 

The 14N quadrupole hyperfine structure was analyzed from the MW spectrum and the nitrogen nuclear quadrupole coupling constants (NQCC) for aniline-Hy are determined as follows xaa = 2.34, Xbb = 1-86 and Xcc = —4.20 MHz38. 

Under anisotropic conditions, NMR lineshapes for a quadrupolar nucleus are dominated by chemical shielding and (first and second order) quadrupolar interactions. Dipolar interaction is usually a minor contribution only. First-order quadrupole interaction lifts the degeneracy of the allowed 21 (i.e. seven in the case of V / = V2) Zeeman transitions as shown in Figure 3.7, giving rise to seven equidistant lines, viz. a central line (mj = + V2 -V2. unaffected by quadrupole interaction) and six satellite lines. The overall breadth of the spectrum is determined by the size of the nuclear quadrupole coupling constant Cq the deviations from axial symmetry and hence the shape of the spectral envelope are governed by the asymmetry parameter. Static solid-state NMR thus provides additional parameters, in particular the quadrupole coupling constant, which correlates with the electronic situation in a vanadium compound. [ 1 The central component reflects the anisotropy of the chemical shift. 

The resulting spectrum represents a weighted average over the rotational states and a careful analysis of it yields the nuclear quadrupole coupling constant. Molecular beam electric resonance is complementary to pure rotational spectroscopy since transitions between the Stark levels of the rotational states (AJ = 0) are observed (sometimes AJ= 1 transitions are also studied). Specially constructed maser spectrometers55 that can detect transitions of rotationally selected molecules have been used to determine very small coupling constants, such as those for deuterium compounds. Again, molecular beam resonance is currently limited to the study of small molecules. 

Deuterium quadrupole coupling constants can also be obtained from electron nuclear double resonance (ENDOR).19 30 An observation of the hyperfine structure caused by quadrupole coupling in the electron paramagnetic resonance (EPR) spectrum, as for many lanthanide complexes, has not been reported for deuterium. The determination of nuclear quadrupole coupling constants from Mossbauer spectroscopy is not applicable to the deuterium nucleus. 

A. C. Legon, P. D. Aldrich, and W. H. Flygare,/. Am. Chem. Soc., 104, 1486 (1982). The Rotational Spectrum, Chlorine Nuclear Quadrupole Coupling Constants, and Molecular Geometry of a Hydrogen-Bonded Dimer of Cyclopropane and Hydrogen Chloride. 

Nuclear quadrupole coupling constants, the dipole moment, and the structure of CIF5 have been redetermined from two new determinations of the microwave spectrum they are in better agreement with one another than with the data... 

The coupling constant J(P-D) = 29.0 0.1 Hz was determined from the ip NMR spectrum of PD3 in the isotropic phase CCI4 and the dipolar coupling constant in the liquid-crystal solvent EBBA (the doublet splitting in the NMR spectrum led to the deuterium nuclear quadrupole coupling constant see p. 157) [3]. 

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