Principles of spin-echo modulation by J-couplings in magic-angle-spinning solid-state NMR

In magic angle spinning solid-state NMR, the homonuclear J-couplings between pairs of spin-1/2 nuclei may be determined by studying the modulation of the spin echo induced by a pi-pulse, as a function of the echo duration. We present the theory of J-induced spin-echo modulation in magic-angle-spinning solids, and derive a set of modulation regimes which apply under different experimental conditions. In most cases, the dominant spin-echo modulation frequency is exactly equal to the J-coupling. Some what surprisingly, the chemical shift anisotropies and dipole-dipole couplings tend to stabilise-rather than obscure-the J-modulation. The theoretical conclusions are supported by numerical simulations and experimental results obtained for three representative samples containing C-13 spin pairs.


Published in:
CHEMPHYSCHEM, 5, 6, 815-833
Year:
2004
Publisher:
WILEY-V C H VERLAG GMBH
ISSN:
1439-4235
Keywords:
Laboratories:




 Record created 2015-01-08, last modified 2018-09-13


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