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

固态核磁共振波谱可以说是最强大的技术，可以提供对分子和材料的原子级结构和动力学了解。物理和生命科学界广泛利用这一分析科学技术来解决与制药、电池材料、催化和蛋白质复合体等相关的广泛系统中的挑战性问题。重要的是，固体核磁共振作为一种分析技术带来的进步随着新核磁共振硬件开发的技术进步而不断增长。固态核磁共振的重要性体现在对英国高场固态核磁共振国家研究设施(NRF)的投资中。核磁共振硬件开发的突破往往出现在魔角旋转(MAS)探头的设计上。MA通过在非常高的频率(高达每秒约150,000转)下对样品进行物理旋转来提高核磁共振谱的灵敏度和分辨率，以消除使固态核磁共振谱变宽和复杂化的相互作用的影响。同时，通常需要在不同温度范围内进行核磁共振测量，以深入了解温度驱动的结构变化，或表征和量化材料中的运动过程。标准的MAS探头通常可以达到-80到+100摄氏度的样品温度范围，但根据运动/结构现象和相互作用的性质，通常有必要在这一范围之外进行测量。探头设计的最新进展使得激光加热探头能够加热到~1000K，制冷剂冷却探头能够冷却到~100K，这代表着可获得的温度范围的显著扩大，并为以前所未有的细节研究结构和动力学提供了一个令人兴奋的机会。在NRF内的两台高场光谱仪中，850 MHz光谱仪的宽口径设计允许使用非标准探头设计进行具有挑战性的实验。作为2020-4 NRF投资的一部分，为850 MHz光谱仪购买激光加热MAS探头的资金已经获得，该探头于2022年初安装，并已成功产出。在这里，我们建议进一步扩大这一世界领先设施的能力和影响，购买最先进的低温冷却低温(LT)MAS探头，能够在低至100K的低温下进行测量。该探头与现有的激光加热探头相结合，将最大限度地扩大MAS实验的可用温度范围，使研究人员更多地接触动态和结构现象，同时由于高磁场而最大限度地提高分辨率和灵敏度。由于波兹曼分布，LTMAS设置本身也提供了三个灵敏度增强的内在因素(对应于实验时间减少了9倍)，这将使以前由于灵敏度较差而无法进行的新实验得以进行。这些优势将潜在地影响在NRF研究的所有系统，但对于低灵敏度四极核的研究将特别有益，这些核在材料科学中非常重要，但在低磁场下的观察会变得复杂。经验丰富的设施管理团队将确保LTMAS探测器得到最大限度的利用。NRF有积极的计划，与英国核磁共振社区和其他社区接触，最主要的是通过Connect NMR UK网络和该设施现有的外展活动，以促进和提高对新硬件功能的认识，并扩大和多样化其用户基础。

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.