Very Low Field 2.35 T Solid State NMR Console and Fast MAS NMR Probe for the Study of Paramagnetic Materials Systems

这项建议的目的是扩大固态核磁共振社区所拥有的能力基础，以便能够有效地利用这一技术来研究更多的材料和化学体系。固体核磁共振通常局限于研究抗磁性材料和化合物，即在其电子结构中没有未配对电子的系统。许多正在开发的现代材料和化学体系具有过渡金属和/或稀土物种作为元素组成的一部分；这将未配对的电子引入这些体系中，从而促进了与传统核磁共振方法不相容的顺磁特性。我们如何处理典型的核磁共振测量的传统思维需要调整，因为在这种情况下，我们追求更高的外部磁场强度的典型驱动力会适得其反。产生顺磁各向异性并随磁场线性移动的电子极化，这些效应极大地削弱了常规的核磁共振数据，从而掩盖了通常所寻找的信息。严重的顺磁性可能会完全阻止某些系统的核磁共振测量。解决这一固态核磁共振挑战的最直接方法是尝试在大大减小(而不是增加)的磁场中进行测量，并以非常高的MAS频率旋转样品。这种低场/快速MAS方法最大限度地增加了从这些系统中阐明核磁共振数据的机会，但这些类型的核磁共振光谱仪在世界范围内是非常稀有的商品。虽然世界各地有数千台核磁共振仪器，其场强为7.05 T(1H为300 MHz)及以上，但只有极少数运行中的低场光谱仪可以进行此类测量；此外，英国在这一光谱学领域没有得到很好的照顾，除非有非常有限的概念验证初步研究证明了这一想法。这一新功能将像传统的固态核磁共振仪器一样易于操作，不需要特定的额外培训即可使用它进行数据采集。这一方法的影响预计将影响催化和能源材料(电池材料、固体氧化物和氢传导燃料电池、储氢材料、负载型金属纳米颗粒系统、沸石、核废料玻璃等)、一般有机金属和无机化学以及新兴医学工程领域(用于肿瘤学和血管生长刺激应用的稀土掺杂生物材料)。还预计，这一方法将跨越EPR等现有技术和DNP等新兴技术，这两种技术都采用不同的策略来操纵顺磁相互作用。预计这些关系将刺激一个更具活力的磁共振社区，使其能够协作解决英国面临的具有挑战性的研究问题。剑桥大学、伯明翰大学、帝国理工学院、玛丽皇后大学、肯特大学、伦敦大学学院和兰开斯特大学的学术合作者以及强生马泰和联合利华等工业合作伙伴都敏锐地意识到这种方法提供的这些新的固态核磁共振可能性和灵活性，并且他们热切期待低场/快速MAS组合可以提供的测量技术的改进。形成该提议的具体目标是：(A)向英国磁共振社区提供共享的低场/快速MAS固态核磁共振资源，这将增强现有的英国固态核磁共振仪器套件，(B)配备最先进的固态核磁共振控制台和能够提供最现代实验的适当快速MAS探头技术；(C)使这一方法与EPR等成熟的表征技术和DNP等新兴实验举措保持一致。

The aim of this proposal is to expand the capability base that solid state NMR community has at its disposal so that more materials and chemistry systems can be effectively studied with this technique. Solid state NMR usually confines itself to the study of diamagnetic materials and compounds; i.e. systems that do not possess unpaired electrons in their electronic structure. Many modern materials and chemical systems being developed possess transition metals and/or rare earth species as part of the elemental composition; these introduce unpaired electrons into these systems and thus promote paramagnetic characteristics which are incompatible with the conventional NMR methodology. Our traditional mindset of how we approach the typical NMR measurement needs to be adjusted as our typical drive to higher external magnetic field strengths is counterproductive in this case. The electron polarisation that gives rise to paramagnetic anisotropies and shifts scales linearly with magnetic field, and these effects greatly detract from conventional NMR data thus masking the information that is normally sought. Severe cases of paramagnetism can preclude the NMR measurement of some systems completely.The most direct way to address this solid state NMR challenge is to attempt measurements in a much reduced (rather than increased) magnetic field, and to spin the sample at very high MAS frequencies. This low field/fast MAS methodology maximises the chance for NMR data to be elucidated from these systems, however these types of NMR spectrometers are very rare commodities worldwide. While many thousand NMR instruments exist throughout the world at fields of 7.05 T (300 MHz for 1H) and above, only a handful of operational low field spectrometers exist to undertake these type of measurements; furthermore, the UK is not well catered for in this field of spectroscopy apart from very limited proof-of-concept pilot studies that have demonstrated this idea. This new capability will be as easy to operate as conventional solid state NMR instrumentation and no specific additional training is required to enable its usage for data acquisition. The impact of this methodology is expected to influence the fields of catalysis and energy materials (battery materials, solid oxide and H conduction fuel cells, hydrogen storage materials, supported metal nanoparticles systems, zeolites, nuclear waste glasses etc.), general organometallc and inorganic chemistry, and the emerging field of medical engineering (rare earth doped biomaterials for oncology and blood vessel growth stimulation applications). It is also expected that this methodology will bridge across to established techniques such as EPR, and emerging technologies such as DNP, both of which employ different strategies for the manipulation of the paramagnetic interaction. These relationships are expected to stimulate a more vibrant magnetic resonance community that will be capable of collaboratively tackling the challenging research issues that confront the UK. Academic collaborators at Cambridge, Birmingham, Imperial, Queen Mary, Kent, UCL and Lancaster, and industrial partners such as Johnson Matthey and Unilever are all acutely aware of these new solid state NMR possibilities and flexibility that this methodology offers, and they eagerly await the improvements to the measurement technology that a low field/fast MAS combination can offer.The specific objectives that shape this proposal are:(a) to deliver a shared low-field/fast MAS solid state NMR resource to the UK magnetic resonance community that will augment the current UK suite of solid state NMR instrumentation in existence,(b) to put in place a state-of-the-art solid state NMR console and appropriate fast MAS probe technology capable of delivering the most modern experiments,(c) to align this methodology with established characterisation technologies such as EPR and emerging experimental initiatives such as DNP.