Closed-cycle cold helium magic-angle spinning for sensitivity-enhanced multi-dimensional solid-state NMR
Publication date: Available online 12 August 2015
Source:Journal of Magnetic Resonance
Author(s): Yoh Matsuki, Shinji Nakamura, Shigeo Fukui, Hiroto Suematsu, Toshimichi Fujiwara
Magic-angle spinning (MAS) NMR is a powerful tool for studying molecular structure and dynamics, but suffers from its low sensitivity. Here, we developed a novel helium-cooling MAS NMR probe system adopting a closed-loop gas recirculation mechanism. In addition to the sensitivity gain due to low temperature, the present system has enabled highly stable MAS (v R = 4 – 12 kHz) at cryogenic temperatures (T = 35 – 120 K) for over a week without consuming helium at a cost for electricity of 16 kW/hr. High-resolution 1D and 2D data were recorded for a crystalline tri-peptide sample at T = 40 K and B 0 = 16.4 T, where an order of magnitude of sensitivity gain was demonstrated versus room temperature measurement. The low-cost and long-term stable MAS strongly promotes broader application of the brute-force sensitivity-enhanced multi-dimensional MAS NMR, as well as dynamic nuclear polarization (DNP)-enhanced NMR in a temperature range lower than 100 K.
Graphical abstract
Source:
Journal of Magnetic Resonance