TR&D 4 -- Advanced Magic Angle Spinning NMR methods

TR

• 批准号: 10224251
• 负责人: ROBERT Guy GRIFFIN
• 金额: $ 3万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-06-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10224251
• 关键词: 2,4-Dinitrophenol; Caliber; Crystallization; Data; Diamond; Frequencies; Gases; Goals; Label; Lasers; Liquid substance; Magic; Magnetic Resonance; Methods; Proteins; Reporting; Sampling; System; Temperature; Testing; Thermal Conductivity; Water; base; cold temperature; cryogenics; design; design and construction; experimental study; improved; instrumentation; microwave electromagnetic radiation; operation; solid state nuclear magnetic resonance; transmission process

Project Summary TR&D 4 proposes to construct a cryogenic recirculation system and an associated MAS probe that will permit high spinning frequency MAS experiments using He gas as a fluid in the 200-250 kHz regime. In addition, the system will function at low temperatures enabling DNP experiments with improved sensitivity. The cryogenic system will involve 4 steps as follows: (1) We plan to design and construct a recirculation system to perform MAS experiments at 80 K that will initially use N2 as a working fluid since it is less expensive and will allow us to assemble and debug the system – insure that does not leak, etc. (2) In the second step we will introduce He into the system as the operating fluid. At ambient temperatures this will provide a means to achieve high spinning frequencies, with the eventual goal being the 200-250 kHz regime. Therefore, this system will be important in performing the experiments in TR&D 1, 2 and 4 and for almost all of the solid state NMR experiments in the DBP’s and CE’s. (3) Once this is functioning we plan to use He at ~20-50 K which will provide another factor of 2-4 in Boltzmann polarization for both conventional NMR and DNP experiments. It could also enable 1H detected DNP experiments. (4) Will construct a MAS probe for low temperature operation based on our transmission line design that has been successfully implemented twice at 500 MHz. Concurrently we plan to develop a new class of MAS rotors fabricated from single crystal diamond. Diamond is the preferred material because of its high strength, excellent thermal conductivity, and it is transparent to microwaves so that it will improve DNP enhancements. Because the rotors are small this is economically feasible. The rotors will probably be laser machined from single crystals with a femtosecond laser and if we are successful in spinning at above 100 kHz at 100 K they will open an entire new field of 1H detected DNP.

项目概要 TR&D 4 提议建造一个低温再循环系统和一个相关的 MAS 探测器，该系统将 允许使用氦气作为 200-250 kHz 范围内的流体进行高旋转频率 MAS 实验。 该系统将在低温下运行，从而提高 DNP 实验的灵敏度。 系统将涉及以下 4 个步骤： (1) 我们计划设计和建造一个再循环系统，在 80 K 下进行 MAS 实验，这将 最初使用 N2 作为工作流体，因为它更便宜并且允许我们组装和调试系统 – 确保不泄漏等。 (2) 在第二步中，我们将在环境温度下将 He 作为工作流体引入系统中。 这将提供一种实现高旋转频率的方法，最终目标是 200-250 kHz 因此，该系统对于执行 TR&D 1、2 和 4 中的实验非常重要。 DBP 和 CE 中的所有固态 NMR 实验。 (3) 一旦该功能发挥作用，我们计划在 ~20-50 K 下使用 He，这将提供另一个 2-4 的因子 用于传统 NMR 和 DNP 实验的玻尔兹曼偏振还可以实现 1H 检测 DNP。 实验。 (4) 将根据我们的传输线设计构造一个用于低温操作的 MAS 探头 已在 500 MHz 下成功实施两次。 同时，我们计划开发一种由单晶金刚石制成的新型 MAS 转子。 金刚石因其高强度、优良的导热性而成为首选材料， 对微波透明，因此可以提高 DNP 的增强效果，因为转子很小。 转子可能会用飞秒激光器对单晶进行激光加工。 如果我们成功地在 100 K 下以 100 kHz 以上的速度旋转，他们将打开一个全新的 1H 检测领域 DNP。