LINEAR ELECTRIC FIELD EFFECT (LEFE) IN ESR

ESR 中的线性电场效应 (LEFE)

• 批准号: 7723870
• 负责人: KEITH A EARLE
• 金额: $ 0.07万
• 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/7723870
• 关键词: Computer Retrieval of Information on Scientific Projects Database; Coupling; Development; Discrimination; Electrodes; Electronics; Electrostatics; Facility Construction Funding Category; Film; Frequencies; Funding; Grant; Institution; Measurement; Methods; Modeling; Physiologic pulse; Proteins; Pulse taking; Range; Research; Research Personnel; Resolution; Resources; Sampling; Series; Shunt Device; Source; Spin Labels; Standards of Weights and Measures; Structure; System; Techniques; Time; United States National Institutes of Health; Work; electric field; experience; insight; liquid crystal; research study; success

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. Electrostatic interactions influence the structure, function, and interaction of proteins with other biomolecules. Thus, methods that probe electrostatics provide complementary information to methods sensitive to dynamics and will aid in the construction of models for interpreting spectra. The availability of high-field/high-frequency-ESR (HFHF-ESR) allows the use of nitroxide spin labels as an accurate probe of local electrostatics in biomolecules. When the electronic energy levels are shifted by interactions with a local electric field, second-order shifts appear in the nitroxide's g-tensor. The excellent g-factor discrimination at high field permits the measurement of these small shifts that are not detectable at standard ESR fields. The sensitivity to local electrostatic effects may be greatly enhanced by the application of a strong external electric field. The possibility of exploiting the high g-factor resolution of HFHF-ESR to observe such effects in organic radicals greatly extends the range of systems that can be examined. The probe necessary for applying a strong local electric field in a high-frequency sample resonator is a natural extension of techniques we have developed for studying electric-field effects in liquid crystals. We are optimizing the thin-film electrode geometry for our standard Fabry-P¿rot (FP) resonator, to permit studies in the E parallel configuration. Development work on a series of shunt FP resonators for use at 95, 170 and 240GHz with variable coupling is underway utilizing time-domain analysis methods developed in the center. These new resonators will allow us to perform experiments in the E perpendicular configuration. The experience we have gained with the center's 95GHz pulse spectrometer has given us important insights into the sample holder requirements that will be necessary for the success of the LEFE experiments.

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 静电相互作用影响蛋白质与其他生物分子的结构、功能和相互作用。 因此，探测静电的方法为对动力学敏感的方法提供了补充信息，并将有助于解释光谱的模型的构建。 高场/高频-ESR（HFHF-ESR）的可用性允许使用氮氧自旋标记作为生物分子中局部静电的精确探针。 当电子能级因与局部电场的相互作用而发生位移时，氮氧化合物的g张量就会出现二阶位移。 在高场下出色的g因子辨别力允许测量这些在标准ESR场下无法检测到的小位移。 通过施加强外部电场，可以大大增强对局部静电效应的灵敏度。利用HFHF-ESR的高g因子分辨率来观察有机自由基中的这种效应的可能性大大扩展了可以检查的系统的范围。 在高频样品谐振器中施加强局部电场所需的探针是我们为研究液晶中的电场效应而开发的技术的自然延伸。我们正在优化我们的标准法布里-珀罗（FP）谐振器的薄膜电极的几何形状，允许在E平行配置的研究。利用该中心开发的时域分析方法，正在开发一系列用于95、170和240 GHz的可变耦合并联FP谐振器。 这些新的谐振器将使我们能够在E垂直配置中进行实验。 我们在该中心的95 GHz脉冲光谱仪上获得的经验使我们对LEFE实验成功所必需的样品保持器要求有了重要的了解。