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Rationalising Heteronuclear Decoupling in Refocussing Applications of Solid‐State NMR Spectroscopy
Author(s) -
Frantsuzov Ilya,
Vasa Suresh K.,
Ernst Matthias,
Brown Steven P.,
Zorin Vadim,
Kentgens Arno P. M.,
Hodgkinson Paul
Publication year - 2017
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201601003
Subject(s) - nutation , heteronuclear molecule , magnetization , decoupling (probability) , solid state nuclear magnetic resonance , magic angle spinning , radio frequency , nuclear magnetic resonance spectroscopy , nuclear magnetic resonance , chemistry , dephasing , frequency offset , spectral line , analytical chemistry (journal) , spectroscopy , two dimensional nuclear magnetic resonance spectroscopy , computational physics , magnetic field , physics , condensed matter physics , computer science , telecommunications , channel (broadcasting) , quantum mechanics , astronomy , control engineering , chromatography , orthogonal frequency division multiplexing , engineering , computer network
Factors affecting the performance of 1 H heteronuclear decoupling sequences for magic‐angle spinning (MAS) NMR spectroscopy of organic solids are explored, as observed by time constants for the decay of nuclear magnetisation under a spin‐echo ( T 2 ' ). By using a common protocol over a wide range of experimental conditions, including very high magnetic fields and very high radio‐frequency (RF) nutation rates, decoupling performance is observed to degrade consistently with increasing magnetic field. Inhomogeneity of the RF field is found to have a significant impact on T 2 ' values, with differences of about 20 % observed between probes with different coil geometries. Increasing RF nutation rates dramatically improve robustness with respect to RF offset, but the performance of phase‐modulated sequences degrades at the very high nutation rates achievable in microcoils as a result of RF transients. The insights gained provide better understanding of the factors limiting decoupling performance under different conditions, and the high values of T 2 ' observed (which generally exceed previous literature values) provide reference points for experiments involving spin magnetisation refocussing, such as 2D correlation spectra and measuring small spin couplings.