Double-quantum excitation in the NMR of spinning solids by pulse-assisted rotational resonance

Karlsson, T., Hughes, C.E., Schmedt auf der Günne, J. and Levitt, M.H. (2001) Double-quantum excitation in the NMR of spinning solids by pulse-assisted rotational resonance. Journal of Magnetic Resonance, 148 (2), 238-247. (doi:10.1006/jmre.2000.2243).

Abstract

We describe a new technique for double-quantum excitation in magic-angle-spinning NMR of powdered solids. The technique is designed to efficiently excite double-quantum coherence in the vicinity of a rotational resonance condition. The offset from rotational resonance allows the double-quantum filtered signals to be observed with high resolution and sensitivity.
The method uses rotational excitation of zero-quantum coherence, assisted by radiofrequency pulse cycles. The zero-quantum coherence is converted into double-quantum coherence by a frequency-selective inversion sequence.
Experiments on [13C2, 15N]-glycine demonstrate a double-quantum filtering efficiency of 41% at a sample rotation frequency of 8.300 kHz, which is 1.600 kHz away from the n = 1 rotational resonance.
We achieve 32% double-quantum filtering efficiency at a spinning frequency of 9.250 kHz, which is 2.550 kHz away from rotational resonance.

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Contributors

Author: M.H. Levitt

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