NEW PROBE HEADS FOR PULSE ESR EXPERIMENTS

用于脉冲 ESR 实验的新型探头

• 批准号: 7723881
• 负责人: Jack H Freed
• 金额: $ 2.32万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2009-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7723881
• 关键词: Attention; Computer Retrieval of Information on Scientific Projects Database; Coupled; Coupling; Data; Electrons; Exhibits; Frequencies; Funding; Generations; Grant; Head; Helium; Hour; Housing; Institution; Liquid substance; Magnetism; Modification; Nitrogen; Physiologic pulse; Pulse taking; Pump; Research; Research Personnel; Resources; Sampling; Source; Spectrum Analysis; Structure; System; Temperature; Time; United States National Institutes of Health; Vacuum; Work; base; cold temperature; cryogenics; cryostat; design; improved; microwave electromagnetic radiation; research study; simulation

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We are using routinely a 17 GHz cryogenic probe-head, based on an Oxford CF935 flow cryostat and a dielectric resonator coupled to Ku-band waveguide. The system allows us to lower the temperature to 4.2 K or less. A turbomolecular pumping station was added to maintain a high vacuum inside the cryostat vacuum jacket making it possible to acquire DQC data continuously at 60-80 K at the sample for 120 hours from a single 60-liter liquid helium storage dewar. Samples can be changed in 2-3 minutes, which is important for studying multiple samples. The resonator accepts 2microL samples and accepts pulses as short as 3.2 ns at optimal coupling. Dead-time is under 39 ns and could be further improved after making modifications to the receiver protector and improving resonator shielding. Other probe-heads for this working frequency and for 9.5 GHz and 35 GHz are being designed using CST Microwave Studio from CST and fabricated with the in-house microwave workbench used for verification. Using CST Microwave studio, the simulations were done for a cavity-type bimodal resonator for double electron-electron resonance spectroscopy (DEER) to be used in work at liquid nitrogen temperatures with an X-band spectrometer equipped with separate pulse sources for two different frequencies. Special attention was paid to design the resonators with improved homogeneity of the magnetic component of the microwave field (B1). This is important for DQC work and for the generation of multi-pulse sequences. Although Bridged Loop Gap resonators could be used, high-power pulses may cause arching. Dielectric resonators while exhibiting high dielectric strength do not feature very homogeneous field. We developed a dielectric resonator (DR) structure with improved homogeneity similar to that of Bridged Loop Gap resonators and designed the DR shield and coupling to rectangular waveguide.

该副本是利用众多研究子项目之一 由NIH/NCRR资助的中心赠款提供的资源。子弹和 调查员（PI）可能已经从其他NIH来源获得了主要资金， 因此可以在其他清晰的条目中代表。列出的机构是 对于中心，这不一定是调查员的机构。 我们通常使用牛津CF935流低温恒温器和与KU波段波导耦合的介电谐振器，通常使用17 GHz的低温探针头。该系统允许我们将温度降低到4.2 K或更少。添加了一个涡轮分子抽水站，以在低温恒温器真空夹克内保持高真空，从而可以在样品下在60-80 K处连续获取DQC数据，从单个60升液体氦储物露水露水中120小时。样品可以在2-3分钟内更改，这对于研究多个样品很重要。谐振器接受2microl样品，并在最佳耦合时接受脉冲短于3.2 ns。死时间不到39 ns，在对接收器保护器进行修改并改善谐振器屏蔽后可以进一步改善。使用CST的CST Microwave Studio设计了此工作频率和9.5 GHz和35 GHz的其他探针头，并使用用于验证的内部微波工作台制造。使用CST微波工作室，对腔型双峰谐振器进行了模拟，以用于双电子 - 电子谐振光谱（DEER），用于在液氮温度下使用带有X频段光谱仪的液体氮气温度，配备了单独的脉冲源，用于两个不同的频率。特别注意通过微波场（B1）的磁成分的均匀性提高谐振器。这对于DQC工作和生成多脉冲序列很重要。 尽管可以使用桥接环间的谐振器，但高功率脉冲可能会导致拱门。介电谐振器在表现出较高的介电强度的同时并不具有非常均匀的磁场。我们开发了一种介电谐振器（DR）结构，具有与桥接环间隙谐振器相似的均匀性，并将盾牌和耦合设计为矩形波导。