Magic-angle spinning solid-state multinuclear NMR on low-field instrumentation

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• 作者：Morten K. S酶rensen ; Oleg Bakharev ; Ole Jensen ; Hans J. Jakobsen ; J酶rgen Skibsted ; Niels Chr. Nielsen
• 关键词：Low-field NMR ; Magic-angle spinning ; 23Na second-order quadrupolar coupling ; 31P&ndash ; 19F dipole&ndash ; dipole coupling ; Sodium nitrate ; Potassium monofluorophosphate
• 刊名：Journal of Magnetic Resonance
• 出版年：January, 2014
• 年：2014
• 卷：238
• 期：Complete
• 页码：20-25
• 全文大小：1004 K

文摘

Mobile and cost-effective NMR spectroscopy exploiting low-field permanent magnets is a field of tremendous development with obvious applications for arrayed large scale analysis, field work, and industrial screening. So far such demonstrations have concentrated on relaxation measurements and lately high-resolution liquid-state NMR applications. With high-resolution solid-state NMR spectroscopy being increasingly important in a broad variety of applications, we here introduce low-field magic-angle spinning (MAS) solid-state multinuclear NMR based on a commercial ACT 0.45 T 62 mm bore Halbach magnet along with a homebuilt FPGA digital NMR console, amplifiers, and a modified standard 45 mm wide MAS probe for 7 mm rotors. To illustrate the performance of the instrument and address cases where the low magnetic field may offer complementarity to high-field NMR experiments, we demonstrate applications for ²³Na MAS NMR with enhanced second-order quadrupolar coupling effects and ³¹P MAS NMR where reduced influence from chemical shift anisotropy at low field may facilitate determination of heteronuclear dipole-dipole couplings.