The UK High-Field Solid-State NMR National Research Facility: EPSRC Core Equipment Award 2022

点击翻译按钮获取中文摘要

Solid-state nuclear magnetic resonance (NMR) spectroscopy is arguably the most powerful technology for providing atomic-level structure and dynamics understanding of molecules and materials. The physical and life sciences communities exploit this analytical science technique extensively to address challenging issues in a wide range of systems relevant to, for example, pharmaceuticals, battery materials, catalysis and protein complexes. Importantly, the advances enabled by solid-state NMR as an analytical technique are continually increasing in line with technological progresses in the development of new NMR hardware. The importance of solid-state NMR is reflected in investment in the UK High-Field Solid-State NMR National Research Facility (NRF). Breakthroughs in NMR hardware development have often been in the design of magic-angle spinning (MAS) probes. MAS improve both the sensitivity and resolution of NMR spectra by physical rotation of the sample at very high frequencies (up to about 150,000 revolutions per second) to remove the effects of interactions that broaden and complicate solid-state NMR spectra. At the same time, it is often desirable to perform NMR measurements at a range of different temperatures to give insight into temperature-driven structural changes, or to characterise and quantify motional processes in materials. Standard MAS probes can typically achieve sample temperatures in the range -80 to +100 C, but it is often necessary to perform measurements outside of this range depending on the nature of the motional/structural phenomena and interactions present. Recent developments in probe design have resulted in the availability of laser-heated probes capable of heating to ~1000 K and cryogen-cooled probes capable of cooling to ~100 K. This represents a significant widening of the accessible temperature range and provides an exciting opportunity to study structure and dynamics in unprecedented detail. Of the two high-field spectrometers within the NRF, the wide-bore design of the 850 MHz spectrometer allows for challenging experiments with non-standard probe designs. As part of the 2020-4 NRF investment, funding to purchase a laser-heated MAS probe for the 850 MHz spectrometer was secured and the probe was installed in early 2022 with already successful outputs. Here, we propose to further extend the capability and impact of this world-leading facility with the purchase of a state-of-the-art cryogenically-cooled low-temperature (LT)MAS probe capable of performing measurements at cryogenic temperatures down to 100 K. The combination of this probe with the existing laser-heated probe will maximise the available temperature range for MAS experiments, giving researchers increased access to dynamic and structural phenomena, while at the same time maximising resolution and sensitivity due to the high magnetic field. Due to the Botzmann distribution, the LTMAS setup itself also provides an intrinsic factor of three sensitivity enhancement (corresponding to a factor of 9 reduction in experimental time) which will enable new experiments to be performed that were previously unfeasible due to poor sensitivity. These advantages will potentially impact all systems studied at the NRF, but will be particularly beneficial for the study of low-sensitivity quadrupolar nuclei, which are of great importance in materials science, but suffer from additional broadening that complicate their observation at low magnetic fields.The highly experienced Facility Management Team will ensure that the LTMAS probe is exploited to its maximum capabilities. The NRF has active program of engaging actions with the UK NMR community and beyond, most notably via the Connect NMR UK network and the Facility's existing activities in outreach, to promote and raise awareness of the new hardware capabilities and to grow and diversify its user base.