Published in

Elsevier, Journal of Magnetic Resonance, (250), p. 25-28

DOI: 10.1016/j.jmr.2014.11.004

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Enhancement of quantum rotor NMR signals by frequency-selective pulses.

This paper was not found in any repository, but could be made available legally by the author.
This paper was not found in any repository, but could be made available legally by the author.

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Data provided by SHERPA/RoMEO

Abstract

Quantum-rotor-induced polarisation (QRIP) enhancement is exhibited by substances which contain freely rotating methyl groups in the solid state, provided that the methyl groups contain a (13)C nucleus. Strong signal enhancements are observed in solution NMR when the material is first equilibrated at cryogenic temperatures, then rapidly dissolved with a warm solvent and transferred into an NMR magnet. QRIP leads to strongly-enhanced (13)C NMR signals, but relatively weak enhancements of the (1)H signals. We show that the (1)H signals suffer from a partial cancellation of degenerate contributions, which may be corrected by applying a frequency-selective π pulse to the inner peaks of the (13)C multiplet prior to (1)H observation.