High Magnetic Field, Time Domain Magnetic Resonance Spectrometers

说明(申请人提供)：拟议的研究集中于开发两个独立的时间域磁共振光谱仪：一个频率为140 GHz(1H频率212 MHz，磁场为5T)，第二个频率为250 GHz(1H频率380 MHz，磁场9T)。这些光谱仪将是世界上第一台工作在100 GHz以上频率的高功率时域光谱仪，现代磁共振实验研究就是在这里进行的。这将应用于动态核极化/核磁共振(DNP/核磁共振)和电子顺磁共振的研究。目前，由于高频微波放大器的匮乏，限制了高频下时间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偏振传输方法的发展成为可能--积分固体效应、装饰态固体效应、电子-核哈特曼-哈恩交叉极化等--这些方法在强磁场下更有利。陀螺放大器对于这些时域实验的实施是必不可少的。时间域电子顺磁共振波谱也将从这一新仪器中受益匪浅。更高的频率可以提供更高的g因子分辨率，包括重叠粉末图案的光谱，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谱的获取和解释。因此，这项提议的第一个目标是将现有的820W、140 GHz陀螺放大器与现有的核磁共振和电子顺磁共振光谱仪集成在一起，并在高功率DNP/核磁共振和电子顺磁共振研究中获得该光谱仪的首次演示。我们将使用一台通用的低温光谱仪，用于研究212 MHz的DNP/NMR和140 GHz的EPR。我们最近成功地使用了低功率(120 MW)光源操作该光谱仪，但必须开发和实施与高功率陀螺放大源配合使用所需的组件。第二个目标是设计和展示用于DNP/核磁共振和EPR的改进的谐振器，如光子晶体谐振器，并开发用于核磁共振应用的必要的辅助THz元件，如用于THz DNP/核磁共振和EPR实验的开关、环行器、传输线等。由于高频商用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是至关重要的。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/核磁共振和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该放大器的开发，功率水平为&gt；100 W。一旦250 GHz陀螺放大器完全研制成功，我们将把它应用于脉冲DNP/核磁共振和电子顺磁共振。合成的系统将成为世界上频率最高的高功率DNP/核磁共振和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.