Tensor quadrupolar coupling

Champmartin D and Rubini P 1996 Determination of the 0-17 quadrupolar coupling constant and of the C-13 chemical shielding tensor anisotropy of the CO groups of pentane-2,4-dione and beta-diketonate complexes in solution. NMR relaxation study/norg. Chem. 35 179-83... 

Fundamental constants (Cx), spatial tensors in the principal axis frame ((fi3 m,)F), and spin tensors (Tjm) for chemical shielding (a), J coupling (J), dipole-dipole (IS), and quadrupolar coupling (Q) nuclear spin interactions (for more detailed definition of symbols refer to [50])... 

F. H. Larsen, H. J. Jakobsen, P. D. ElUs and N. C. Nielsen, Sensitivity-enhanced quad-rupolar-echo NMR of half-integer quadrupolar nuclei. Magnitudes and relative orientation of chemical shielding and quadrupolar coupling tensors. /. Phys. Chem. A, 1997, 101,8597-8606. 

Classically, the electric field gradient at a nucleus is produced by the arrangement of charges (i.e., other nuclei and electrons) about that nucleus 66). If the nucleus is quad-rupolar, as in the case of 27A1, then the interaction of its nuclear quadrupole moment, eQ, with the largest component of the EFG tensor, V33, is defined as the quadrupolar coupling constant, CQ ... 

Fig. 30. 2H NMR data for 26% benzene-d6 in PS (M — 1020g/mol) at different temperatures (7g = 240 K) (a) ID spectra and (b) experimental and simulated 2D spectra (lm = 100ms).183 At the temperatures studied, the six-fold jump of the benzene molecules is fast on the NMR time scale (r < 1 / ) so that its mere consequence is a pre-averaging of the quadrupolar coupling tensor.

Thus, the quadrupolar relaxation mechanism depends on the TCF of the EFG. The square root of the amplitude of the TCF, that is the strength of the EFG, is denoted the quadrupolar coupling constant and is commonly discussed separately from its correlation time. In isotropic systems, the errors in the results from the MD simulations can be reduced by realizing that the TCF of the Oth-component of the EFG tensor is proportional to the TCF of the whole EFG tensor within a... 

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