High Power 200 GHz Pulsed/Continuous Wave (CW) Microwave Source for Dynamic Nuclear Polarization (DNP) Spectroscopy

我们的愿景是创造一种用于核磁共振(核磁共振)的光谱仪，它可以检测到即使是最好的传统光谱仪也能探测到的信号，这些信号的强度比最好的传统光谱仪的信号弱数百倍。核磁共振方法作为化学中的主要分析工具已经牢固确立，在材料科学的表征方面具有越来越大的影响力，并使医学成像发生了革命性的变化。尽管核磁共振技术取得了巨大的成功，但仍有巨大的需求需要通过提高该技术的灵敏度和速度来突破这一界限。这将使核磁共振能够用于研究广泛的问题，包括催化、电池和燃料电池，在这些问题上，由于缺乏敏感性，它的影响有限。此外，人们普遍认识到，结构信息是理解生物过程(如蛋白质折叠、信号转导等)的关键。而许多问题只有在核磁共振的灵敏度显著提高的情况下才能得到解决。动态核极化(DNP)通过利用电子自旋固有的比核自旋大得多的极化(例如，13C的~2500倍)，提供了极大地提高核磁共振灵敏度的令人兴奋的可能性。沃里克的DNP基础设施由374万GB的基本技术项目(EP/D045967/1)资助。所开发的DNP系统的所有部件的功能都达到或高于其设计目标，但回旋微波源不符合常规操作/开发所需的功率/稳定性要求。尽管如此，还是取得了很大的改进(60倍)。与目前使用的回旋管微波源相比，拟议的新“交钥匙”微波源将提供显著增强的性能，更稳定、更灵活、更多用途，并且运行成本显著降低。它将使沃里克的DNP能力继续快速发展和利用。开发工作将与诺丁汉大学、圣安德鲁斯大学和南安普顿大学的研究人员合作完成，而增强的DNP能力将被更广泛的充满活力的英国MR社区利用，他们将能够使用一种工具，使以前无法实现的系统研究成为可能。这项研究的影响将是巨大的，因为许多应用中的灵敏度增强可能超过几百倍。新的能力当然将通过拟议的试点研究来刺激尚未预见的活动。该项目的目标是：(A)为CW DNP增强型固态核磁共振提供共享的英国资源，成本仅为目前能力较差的商业系统的一小部分，并且性能优于当前技术水平。(B)开发比目前的连续波方法灵敏度更高的脉冲DNP技术。这是可能的，因为新的源可以提供微波脉冲以及连续输出，这将是一种独特的能力。(C)利用电子弛豫时间较短的极化光源进行DNP研究。这是可能的，因为新的微波源的高功率和多功能性，并应极大地扩大增强技术的适用范围。

Our vision is to create a spectrometer for Nuclear Magnetic Resonance (NMR) that can detect signals that are hundreds of times weaker than can be achieved with even the very best conventional spectrometers. NMR methods are firmly established as a primary analytical tool in chemistry, are increasingly influential for characterisation in materials science and have revolutionised medical imaging. Despite the great success of NMR there remains a huge demand to push the boundaries by increasing the sensitivity and speed of the technique. This will enable NMR to be used in the study of a broad range of problems, including catalysis, batteries and fuel cells where today its impact is limited through lack of sensitivity. Furthermore, it is widely appreciated that structural information is key for understanding biological processes (e.g. protein folding, signal transduction etc.) and many problems will only be soluble if the sensitivity of NMR is dramatically increased. Dynamic Nuclear Polarisation (DNP) offers the exciting possibility to greatly increase the sensitivity of NMR by exploiting the inherently much larger polarisation of electron spins as compared to nuclear spins (e.g. ~ 2500 times for 13C). The DNP infrastructure at Warwick was funded by a £3.74M Basic Technology project (EP/D045967/1). All components of the DNP systems developed functioned at or above their design targets, except for the gyrotron microwave source which did not meet the necessary power/stability requirements for routine operation/exploitation. Nevertheless, large enhancements (60x) were achieved. The proposed new "turn-key" microwave source will provide significantly enhanced performance, is much more stable, agile, versatile and has significantly lower running costs than the gyrotron microwave source used to date. It will enable the continued rapid development and exploitation the DNP capabilities at Warwick. Development work will be done in collaboration with researchers at the Universities of Nottingham, St Andrews and Southampton while the enhanced DNP capabilities will be exploited by the wider vibrant UK MR community who will have access to a tool which enables research on systems previously out of reach. The research impact will be significant since the sensitivity enhancements in many applications are likely to be in excess of a few 100 times. The new capability will of course stimulate as yet unforeseen activities through the proposed pilot studies. The project objectives are: (a) Provision of a shared UK resource for CW DNP-enhanced solid-state NMR at a fraction of the cost of the current less able commercial system and with performance better than the current state of the art. (b) The development of pulsed DNP techniques with higher sensitivity than the current CW methodologies. This is possible because the new source can provide microwave pulses as well as continuous output and would be a unique capability. (c) DNP studies utilizing polarization sources with short electron relaxation times. This is possible because of the high power and versatility of the new microwave source and should greatly enhance the range of applicability of the enhancement technique.