Abstract

Multiple-quantum relaxation in the magic-angle-spinning NMR of 13C spin pairs,

T. Karlsson, A. Brinkmann, P. J. E. Verdegem, J. Lugtenburg, and M. H. Levitt,
Solid-State NMR 14, 43-58, (1999).

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We determine the decay rate constants of zero-, double- and single-​quantum coherence for 13C2 spin pairs in magic-​angle-​spinning solid-​state NMR. The double-​quantum coherence is excited by a C7 pulse sequence and converted into zero-​quantum coherence by a frequency-​selective pair of π/2 pulses. The zero-​quantum coherence is reconverted into observable magnetization by a second pair of π/2 pulses followed by a second C7 sequence. In a magnetically dilute system where the 13C–13C distance is 0.296 nm, the relaxation rate constants are consistent with a model of uncorrelated random fields at the two labeled 13C sites. In a fully-​labelled system with a short 13C–13C distance of 0.153 nm, the measured rate constants are inconsistent with the uncorrelated random field model.

Dr. Andreas Brinkmann
Measurement Science and Standards
National Research Council
1200 Montreal Road, M-40
Ottawa, Ontario K1A 0R6
Canada
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Andreas.Brinkmann@nrc-cnrc.gc.ca
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