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

Krishnan , VV and Kumar, Anil (1991) Dipolar cross-correlation effects in the nuclear overhauser experiments of weakly and strongly coupled spins. In: Journal of Magnetic Resonance (1969), 92 (2). pp. 293-311.

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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:	Journal Article
Publication:	Journal of Magnetic Resonance (1969)
Publisher:	Elsevier science
Additional Information:	Copyright of this article belongs to Elsevier science.
Keywords:	Magnetic-Relaxation;Multispin Systems;C-13 Relaxation;Effect Spectra;Nmr;Spectroscopy;Biomolecules;Conformation; Simulation;Proteins.
Department/Centre:	Division of Chemical Sciences > Sophisticated Instruments Facility (Continued as NMR Research Centre) Division of Physical & Mathematical Sciences > Physics
Date Deposited:	16 Nov 2010 10:42
Last Modified:	16 Nov 2010 10:42
URI:	http://eprints.iisc.ac.in/id/eprint/33737

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