Dipolar cross-correlation effects in the nuclear overhauser experiments of weakly and strongly coupled spins

Krishnan, V. V. ; Anil Kumar, (1991) Dipolar cross-correlation effects in the nuclear overhauser experiments of weakly and strongly coupled spins Journal of Magnetic Resonance, 92 (2). pp. 293-311. ISSN 0022-2364

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Official URL: http://www.sciencedirect.com/science/article/pii/0...

Related URL: http://dx.doi.org/10.1016/0022-2364(91)90271-T

Abstract

The effect of dipolar cross correlation in 1H-1H nuclear Overhauser effect experiments is investigated by detailed calculation in an ABX spin system. It is found that in weakly coupled spin systems, the cross-correlation effects are limited to single-quantum transition probabilities and decrease in magnitude as ωΤc increases. Strong coupling, however, mixes the states and the cross correlations affect the zero-quantum and double-quantum transition probabilities as well. The effect of cross correlation in steady-state and transient NOE experiments is studied as a function of strong coupling and ωΤc. The results for steady-state NOE experiments are calculated analytically and those for transient NOE experiments are calculated numerically. The NOE values for the A and B spins have been calculated by assuming nonselective perturbation of all the transitions of the X spin. A significant effect of cross correlation is found in transient NOE experiments of weakly as well as strongly coupled spins when the multiplets are resolved. Cross correlation manifests itself largely as a multiplet effect in the transient NOE of weakly coupled spins for nonselective perturbation of all X transitions. This effect disappears for a measuring pulse of 90° or when the multiplets are not resolved. For steady-state experiments, the effect of cross correlation is analytically zero for weakly coupled spins and small for strongly coupled spins.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
ID Code:72677
Deposited On:29 Nov 2011 03:54
Last Modified:29 Nov 2011 03:54

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