High Magnetic Field, Time Domain Magnetic Resonance Spectrometers

项目描述（申请人提供）：拟研制两台独立的时域磁共振光谱仪：一台频率为140 GHz (1H频率为212 MHz，磁场为5T)，另一台频率为250 GHz （1H频率为380 MHz，磁场为9T）。这些光谱仪将是世界上第一台工作频率超过100千兆赫的高功率时域光谱仪，用于进行现代磁共振实验研究。将应用于时域动态核极化/核磁共振（DNP/NMR）和EPR研究。目前，由于高频微波放大器的缺乏，限制了高频时域磁共振技术的全面实施。高频微波放大器的出现将使基于相干过程的极化转移方法得以发展，如积分固体效应、变位固体效应、电子-核哈特曼-哈恩交叉极化等，这些方法在高磁场下更有利。陀螺放大器是实现这些时域实验的必要条件。时域EPR光谱学也将受益于这种新的仪器。更高的频率可以为由重叠粉末图案组成的光谱提供更高的g因子分辨率，更精确地测量g-张量、超精细张量和偶极张量的相对取向，并将进一步简化脉冲ENDOR光谱的获取和解释。因此，本提案的第一个目标是将现有的820W， 140 GHz陀螺仪放大器与现有的NMR和EPR光谱仪集成，并获得光谱仪在高功率DNP/NMR和EPR研究中的首次演示。我们将使用设计用于研究DNP/NMR在212 MHz和EPR在140 GHz的多功能低温光谱仪。我们最近已经成功地使用低功率（120兆瓦）源操作该光谱仪，但必须开发和实现与高功率陀螺放大器源一起使用所需的组件。第二个目标是为DNP/NMR和EPR设计和演示改进的谐振器，如光子晶体谐振器，并为NMR应用开发必要的辅助太赫兹元件，如太赫兹DNP/NMR和EPR实验的开关、环行器、传输线等。由于商用高频仪器的稀缺性和高成本，开发这些组件以有效地传输和应用可用的相干辐射至关重要。第三个具体目标是完成现有的14w， 250 GHz陀螺放大器的开发，并将该放大器应用于脉冲DNP/NMR和EPR研究。我们首先计划在提案的第一年使用改进的陀螺放大器设计完成功率水平为bbbb100 W的放大器的开发。一旦250ghz陀螺放大器研制成功，我们将把它应用于脉冲DNP/NMR和EPR。由此产生的系统将是世界上频率最高的大功率DNP/NMR和EPR光谱仪。

DESCRIPTION (provided by applicant): The proposed research is focused on the development of two separate time domain magnetic resonance spectrometers: one at a frequency of 140 GHz (1H frequency of 212 MHz, magnetic field of 5T) and the second at a frequency of 250 GHz (1H frequency of 380 MHz, magnetic field of 9T). These spectrometers will be the world's first high power time domain spectrometers operating at frequencies above 100 GHz where modern magnetic resonance experimental research is conducted. The application will be in time domain dynamic nuclear polarization/nuclear magnetic resonance (DNP/NMR) and EPR research. Currently, the full implementation of time domain magnetic resonance techniques at high frequency is restricted by the paucity of high frequency microwave amplifiers. The advent of high frequency microwave amplifiers will permit the development of polarization transfer methods based on coherent processes the integrated solid effect, the dressed state solid effect, electron-nuclear Hartmann-Hahn cross polarization, etc. -- which are more favorable at high magnetic fields. Gyroamplifiers are essential for the implementation of these time domain experiments. Time domain EPR spectroscopy will also benefit greatly from this new instrumentation. The higher frequency can offer increased g-factor resolution for spectra consisting of overlapping powder patterns, the more precise measurements of the relative orientation of g-, hyperfine and dipolar tensors, and it will further simplify the acquisition and interpretation of pulsed ENDOR spectra. Accordingly, the first goal of this proposal is to integrate an existing 820W, 140 GHz gyroamplifier with an existing NMR and EPR spectrometer and to obtain first demonstrations of the spectrometer in high power DNP/NMR and EPR research. We will use a versatile low temperature spectrometer designed for the study of DNP/NMR at 212 MHz and EPR at 140 GHz. We have recently successfully operated this spectrometer using a low power (120 mW) source, but must develop and implement the components needed for its use with the high power gyroamplifier source. The second goal is to design and demonstrate improved resonators for DNP/NMR and EPR, such as photonic crystal resonators, and to develop the necessary ancillary THz components for the NMR application, such as switches, circulators, transmission lines, etc. for THz DNP/NMR and EPR experiments. Because of the scarcity and high cost of commercial instrumentation at high frequencies, it is crucial to develop these components to efficiently transmit and apply the available coherent radiation. The third specific aim is to complete the development of an existing 14 W, 250 GHz gyroamplifier and to apply that amplifier to pulsed DNP/NMR and EPR research. We first plan to finish the development of this amplifier at a power level of > 100 W using improved gyroamplifier designs in the first year of the proposal. Once the 250 GHz gyroamplifier is fully developed, we will apply it to pulsed DNP/NMR and EPR. The resultant system will then be the highest frequency high power DNP/NMR and EPR spectrometer in the world.