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.

项目摘要 TR＆D 4提案构建一个低温再循环系统和相关的MAS探针，该探针将 在200-250 kHz制度中，允许使用HE气体作为流体进行高旋转频率MAS实验。此外， 该系统将在低温下发挥作用，从而实现DNP实验，并提高灵敏度。低温 系统将涉及4个步骤，如下： （1）我们计划设计和构建一个循环系统，以在80 K处进行MAS实验 最初将N2用作工作流体，因为它价格便宜，并且可以使我们组装和调试系统 - 确保不会泄漏等等。 （2）在第二步中，我们将把他作为操作流体引入系统。在环境温度下 这将为实现高旋转频率提供一种手段，事件目标是200-250 kHz 政权。因此，该系统对于在TR＆D 1、2和4中执行实验非常重要，并且几乎是 DBP和CE的所有固态NMR实验。 （3）一旦运行起来，我们计划在〜20-50 K处使用HE，这将提供另一个2-4的因子 用于常规NMR和DNP实验的Boltzmann极化。它也可以启用1小时检测到的DNP 实验。 （4）将根据我们的传输线设计构建MAS探针，以进行低温操作 已成功实施了500 MHz两次。 同时，我们计划开发一类新的MAS转子，该MAS转子由单晶钻石制造而成。 钻石是首选材料，因为其高强度，出色的导热率，并且是 对微波透明，以改善DNP增强功能。因为转子很小，这是 经济上可行。转子可能是用飞秒激光从单晶加工的激光器 而且，如果我们在100 K时成功旋转100 kHz以上，他们将打开整个1小时的新领域 DNP。