Static quadrupolar coupling constant

A spectrum of perdeuterated potassium laurate in oriented soap-water multilayers (5) is presented in Figure 2. The measured quadrupolar coupling constants are much smaller than those of a static C-D bond, which are about 167 kHz (6) the residual quadrupolar splittings... 

Solid State 170 NMR Spectral Analysis. The 170 nucleus has a 5/2 spin and so has a quadrupolar moment. This means that static and MAS 170 NMR spectrum contains information about quadrupolar interactions and the chemical shift. In order to obtain the quadrupolar coupling constant and chemical shift separately, we have carried out spectral analysis with theoretical calculation taking into account quadrupolar interactions and chemical shift interactions. 

Superhyperfine interactions are rarely observed in the ESR spectrum of the VO + ion because the unpaired electron interacts only weakly with the hgand nuclei, so that often the size of the coupling is less than the ESR bandwidth. This problem has been surmounted through the use of ENDOR spectroscopy. In ENDOR spectroscopy, molecules with their V=0 axes either parallel or perpendicular to the direction of the static magnetic field are selectively irradiated. In this way, the anisotropic superhyperfine coupling constants of H and " N and the " N quadrupolar coupling constants can be obtained. 

By simulating the extracted quadrupolar profiles, four nonequivalent structure units of kyanite, 241— 44, were characterized by the isotropic chemical shifts 5qs, = 13.0, 4.0, 5.7, and 5.9 ppm, the quadrupolar coupling constant Q c = 10.1, 3.8, 6.4, and 9.2 MHz, and the asymmetry parameter rj = 0.27, 0.85, 0.70, and 0.38, respectively [76]. Kyanite thus represents a system with considerable distribution of quadrupolar coupling constants while the distribution of isotropic chemical shifts is less significant. This situation can lead to a counterintuitive decrease in the dispersion of Al 3Q NMR signals in the indirect 3Q dimension Fj with increasing intensity of the static magnetic field (Fig. 18). 

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. 

Trend in chemical shifts, relaxation times, and quadrupolar coupling reported by Yamagata Hackeloer and Kanert use gradient-elastic constants determined through monitoring change in spectrum with static elastic stress... 

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