Quadrupolar relaxation mechanism

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... 

For Mn, a sensitivity of 0.016 ppmK was measured for a KMnO4 solution at a Larmor frequency of 19.087 MHz. An extensive study of the temperature dependence of Mn chemical shifts and linewidths contains data for more than 14 compounds.within the series of compounds Mn(CNR)6 the Mn chemical shifts increased linearly with temperature over the range 238 to 318 K, with coefficients between roughly 0.4 and 0.7 ppmK" . The linewidths also decreased monotically with temperature for all R groups, except for methyl and ethyl, corresponding to a dominant quadrupolar relaxation mechanism, where the linewidth is inversely proportional to temperature. The increase in linewidth with temperature for these two smaller complexes was explained by assuming that spin-rotational relaxation was the dominant mechanism. 

The quadrupolar relaxation mechanism is only directly relevant for those nuclei that have a nuclear spin quantum number, I, greater than V2 (quadrupolar nuclei) and is often the dominant relaxation process for these. This can also be a very efficient mechanism and the linewidths of many such nuclei can be hundreds or even thousands of hertz wide. The properties of selected nuclei with I > V2 are summarised in Table 2.3. Whilst the direct observation of these... 

Although the results on counterion distributions in nucleic acid systems from X-ray crystallography are fragmentary, there exist several NMR studies about metals in DNA systems. - The data from NMR experiments proved to be difficult to interpret. The quadrupolar relaxation mechanism of this nuclide, originating from the electric field gradients, obfuscates the results, but in general the data are consistent with the counterion condensation theory. 

The quadrupolar relaxation mechanism is the dominant process for nuclei with spins greater than j. Quadrupolar relaxation efficiency is determined by... 

Both the 1 B and B n.m.r. spectra of 1.2-D2-I.Z-CgBio lO were used In a study of B quadrupole coupling.Spin-lattice (T].) relaxation times were aeaured. It was concluded that Ti values were dominated by the quadrupolar relaxation mechanism whereas there was a substantial boron-boron scalar contribution to 2 times. The quadrupole coupling constants from this solution study were In good agreement with the data from a solid state B n.q.r. Investigatlon b solid state B, and... 

Chemical shift anisotropy has also been noted for cobalt complexes as a Bg-dependent component to relaxation which, for quadrupolar nuclei, is otherwise dominated by the quadrupolar relaxation mechanism T2 (1-i- /3)Tc, where... 

The Hamilton operator H (t) describing the interaction of the spin system with the bath can, for the quadrupolar relaxation mechanism, be written as a function of space quantized operators and time dependent bath functions... 

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