Research Article

Low-load rotor-synchronised Hahn-echo pulse train (RS-HEPT) 1H decoupling in solid-state NMR: factors affecting MAS spin-echo dephasing times

  1. John M. Griffin1,
  2. Carmen Tripon2,
  3. Ago Samoson3,
  4. Claudiu Filip2,
  5. Steven P. Brown1,*

Article first published online: 21 DEC 2007

DOI: 10.1002/mrc.2145

Issue

Magnetic Resonance in Chemistry

Magnetic Resonance in Chemistry

Special Issue: New techniques in solid-state NMR

Volume 45, Issue S1, pages S198–S208, December 2007

Additional Information

How to Cite

Griffin, J. M., Tripon, C., Samoson, A., Filip, C. and Brown, S. P. (2007), Low-load rotor-synchronised Hahn-echo pulse train (RS-HEPT) 1H decoupling in solid-state NMR: factors affecting MAS spin-echo dephasing times. Magn. Reson. Chem., 45: S198–S208. doi: 10.1002/mrc.2145

Author Information

  1. 1

    Department of Physics, University of Warwick, Coventry, CV4 7AL, UK

  2. 2

    National Institute for R & D of Isotopic and Molecular Technologies, 400293 Cluj, Romania

  3. 3

    National Institute for Chemical Physics and Biophysics, Akadeemia Tee 23, Tallinn, Estonia

*Department of Physics, University of Warwick, Coventry, CV4 7AL, UK.

Publication History

  1. Issue published online: 21 DEC 2007
  2. Article first published online: 21 DEC 2007
  3. Manuscript Accepted: 16 OCT 2007
  4. Manuscript Revised: 12 OCT 2007
  5. Manuscript Received: 13 JUL 2007

Funded by

  • EPSRC
  • Royal Society
  • University of Warwick
  • Estonian Science Foundation

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Keywords:

  • NMR;
  • 1H;
  • 13C;
  • 15N;
  • MAS;
  • spin-echo;
  • low-load 1H decoupling;
  • dephasing times

Abstract

Transverse dephasing times T2′ in spin-echo MAS NMR using rotor-synchronised Hahn-echo pulse-train (RS-HEPT) low-load 1H decoupling are evaluated. Experiments were performed at 300 and 600 MHz for 13CH-labelled L-alanine and 15NH(δ)-labelled L-histidine·HCl·H2O, together with SPINEVOLUTION simulations for a ten-spin system representing the crystal structure environment of the 13CH carbon in L-alanine. For 30 kHz MAS and ν1(1H) = 100 kHz at 300 MHz, a RS-HEPT T2′ value of 17 ± 1 ms was obtained for 13CH-labelled L-alanine which is ∼50% of the XiX T2′ value of 33 ± 2 ms. Optimum RS-HEPT decoupling performance is observed for a relative phase of alternate RS-HEPT π–pulses, Δϕ = ϕ′− ϕ, between 40 and 60° . For experiments at 600 MHz and 30 kHz MAS with 13CH-labelled L-alanine, the best RS-HEPT (ν1(1H) = 100 kHz) T2′ value was 3 times longer than that observed for low-power continuously applied sequences with ν1(1H) ⩽40 kHz, i.e. corresponding to the same average power dissipated in the probe. A marked improvement in RS-HEPT 1H decoupling is observed for increasing MAS frequency: at 55.6 kHz MAS, a best RS-HEPT T2′ value of 34 ± 5 ms was recorded for 13CH-labelled L-alanine. Much improved RS-HEPT broadband performance was also observed at 55.6 kHz MAS as compared to 30 kHz MAS. Copyright © 2007 John Wiley & Sons, Ltd.

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