Enhancement of quantum rotor NMR signals by frequency-selective pulses

Soumya Singha Roy; Jean-Nicolas Dumez; Gabriele Stevanato; Benno Meier; Joseph T. Hill-Cousins; Richard C. D. Brown; Giuseppe Pileio; Malcolm H. Levitt

doi:10.1016/j.jmr.2014.11.004

Enhancement of quantum rotor NMR signals by frequency-selective pulses

Soumya Singha Roy, Jean-Nicolas Dumez, Gabriele Stevanato, Benno Meier, Joseph T. Hill-Cousins, Richard C. D. Brown, Giuseppe Pileio, Malcolm H. Levitt^*

^*Corresponding author for this work

Chemistry

Research output: Contribution to journal › Article › peer-review

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 ¹³C 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 ¹³C NMR signals, but relatively weak enhancements of the ¹H signals. We show that the ¹H 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 ¹³C multiplet prior to ¹H observation.

Original language	English
Pages (from-to)	25-28
Number of pages	4
Journal	Journal of Magnetic Resonance
Volume	250
Early online date	20 Nov 2014
DOIs	https://doi.org/10.1016/j.jmr.2014.11.004
Publication status	Published - Jan 2015

Keywords

Hyperpolarisation
Long-lived states
Methyl groups
QRIP
Quantum-rotor-induced polarization
Tunneling

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10.1016/j.jmr.2014.11.004

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title = "Enhancement of quantum rotor NMR signals by frequency-selective pulses",

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 13C 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 13C NMR signals, but relatively weak enhancements of the 1H signals. We show that the 1H 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 13C multiplet prior to 1H observation.",

keywords = "Hyperpolarisation, Long-lived states, Methyl groups, QRIP, Quantum-rotor-induced polarization, Tunneling",

author = "Roy, {Soumya Singha} and Jean-Nicolas Dumez and Gabriele Stevanato and Benno Meier and Hill-Cousins, {Joseph T.} and Brown, {Richard C. D.} and Giuseppe Pileio and Levitt, {Malcolm H.}",

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T1 - Enhancement of quantum rotor NMR signals by frequency-selective pulses

AU - Roy, Soumya Singha

AU - Dumez, Jean-Nicolas

AU - Stevanato, Gabriele

AU - Meier, Benno

AU - Hill-Cousins, Joseph T.

AU - Brown, Richard C. D.

AU - Pileio, Giuseppe

AU - Levitt, Malcolm H.

PY - 2015/1

Y1 - 2015/1

N2 - 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 13C 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 13C NMR signals, but relatively weak enhancements of the 1H signals. We show that the 1H 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 13C multiplet prior to 1H observation.

AB - 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 13C 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 13C NMR signals, but relatively weak enhancements of the 1H signals. We show that the 1H 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 13C multiplet prior to 1H observation.

KW - Hyperpolarisation

KW - Long-lived states

KW - Methyl groups

KW - QRIP

KW - Quantum-rotor-induced polarization

KW - Tunneling

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EP - 28

JO - Journal of Magnetic Resonance

JF - Journal of Magnetic Resonance

SN - 1090-7807

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Enhancement of quantum rotor NMR signals by frequency-selective pulses

Abstract

Keywords

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