Advanced instrumentation for DNP-enhanced MAS NMR for higher magnetic fields and lower temperatures
Advanced instrumentation for DNP-enhanced MAS NMR for higher magnetic fields and lower temperatures
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DOI：
10.1016/j.jmr.2016.01.022
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发表时间：
2016-03-01
影响因子：
2.2
通讯作者：
Fujiwara, Toshimichi
中科院分区：
文献类型：
--
作者：
Matsuki, Yoh;Idehara, Toshitaka;Fujiwara, Toshimichi
利用动态核极化（DNP）提高MAS NMR的灵敏度在中等场（B-o < 9 T）和温度（T > 90 K）下具有重要意义，在化学和材料科学中具有潜在的应用。然而，考虑到要研究的系统的尺寸和复杂性不断增加，在更高的现场条件下建立DNP是至关重要的，其中光谱分辨率和基本NMR灵敏度趋于提高。从这个角度来看，我们概述了我们最近的努力，硬件的发展，特别是针对提高DNP MAS NMR在高领域。其中包括陀螺仪的开发，可为我们的395 GHz-600 MHz和460 GHz-700 MHz DNP NMR光谱仪实现连续频率调谐和快速频率调制。后一个700 MHz系统涉及两个陀螺仪和一个准光传输系统，该系统将两个独立的亚毫米波组合成单个二向色波。我们还描述了两个低温MAS NMR探针系统，分别在类似于100 K和类似于30 K的温度下工作。后者系统采用了一种新的闭环氦再循环机制，实现低温MAS，而不消耗任何冷冻剂。这些仪器应共同促进高场DNP向更有效，可靠和负担得起的技术发展。一些实验DNP结果与这些仪器。(C)2016年6月，作者。爱思唯尔公司出版
Sensitivity enhancement of MAS NMR using dynamic nuclear polarization (DNP) is gaining importance at moderate fields (B-o < 9 T) and temperatures (T > 90 K) with potential applications in chemistry and material sciences. However, considering the ever-increasing size and complexity of the systems to be studied, it is crucial to establish DNP under higher field conditions, where the spectral resolution and the basic NMR sensitivity tend to improve. In this perspective, we overview our recent efforts on hardware developments, specifically targeted on improving DNP MAS NMR at high fields. It includes the development of gyrotrons that enable continuous frequency tuning and rapid frequency modulation for our 395 GHz-600 MHz and 460 GHz-700 MHz DNP NMR spectrometers. The latter 700 MHz system involves two gyrotrons and a quasi-optical transmission system that combines two independent sub-millimeter waves into a single dichromic wave. We also describe two cryogenic MAS NMR probe systems operating, respectively, at T similar to 100 K and similar to 30 K. The latter system utilizes a novel closed-loop helium recirculation mechanism, achieving cryogenic MAS without consuming any cryogen. These instruments altogether should promote high-field DNP toward more efficient, reliable and affordable technology. Some experimental DNP results obtained with these instruments are presented. (C) 2016 The Authors. Published by Elsevier Inc.