CIRCULAR DICHROISM ESR

圆二色性 ESR

• 批准号: 8363942
• 负责人: KEITH A EARLE
• 金额: $ 0.14万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8363942
• 关键词: Affect; Biology; Chemistry; Circular Dichroism; Code; Electron Spin Resonance Spectroscopy; Frequencies; Funding; Grant; Heating; Morphologic artifacts; National Center for Research Resources; Optics; Principal Investigator; Research; Research Infrastructure; Resources; Sampling; Signal Transduction; Source; Techniques; Technology; Testing; United States National Institutes of Health; absorption; cost; flexibility; magnetic field; prevent

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. One of the important issues that affects the applicability of ESR spectroscopy to a wide range of problems in chemistry and biology is the constraint of magnetic field modulation on the S/N. In order to maximize the signal, one needs modulation amplitudes that are comparable to the linewidth. For high-field/high-frequency-ESR (HFHF-ESR), Lorentz forces limit field modulation amplitudes to less than 20G in order to prevent excessive sample heating. However, many HFHF-ESR linewidths are often greater than 100G, and so it is desirable to develop alternatives to field modulation. In general, some form of signal coding is usually necessary to have an observable signal. We are currently exploring the possibility of using techniques that are common in optical circular dichroism (CD) spectropolarimeters and adapting them to a HFHF-ESR spectrometer to modulate the ESR resonance without using magnetic field modulation. We call the technique CD-ESR. The technique relies on illuminating the ESR sample with two oppositely circularly polarized beams in alternation at a given reference frequency. There is preferential absorption within the ESR sample of one of the circular polarization states which satisfies the so-called Transfer of Modulation principle. Recent efforts have focused on developing a polarization modulator with equal amplitudes of both circular polarization states in order to minimize instrumental artifacts. The recent upgrades that we have made to our HFHF ESR spectrometers will facilitate the implementation of this technique. We are also currently investigating the possibility that our cw sources at 170 and 240GHz may be modified to provide a rugged, reliable means for achieving the necessary polarization modulation. The modified reflection bridge we are implementing is sufficiently flexible to allow for us to test these ideas in a straightforward way.

该副本是利用资源的众多研究子项目之一 由NIH/NCRR资助的中心赠款提供。对该子弹的主要支持 而且，副投影的主要研究员可能是其他来源提供的 包括其他NIH来源。 列出的总费用可能 代表subproject使用的中心基础架构的估计量， NCRR赠款不直接向子弹或副本人员提供的直接资金。 影响ESR光谱对化学和生物学中广泛问题的适用性的重要问题之一是磁场调制对S/N的限制。 为了最大化信号，需要与线宽相当的调制幅度。对于高场/高频 - ESR（HFHF-ESR），Lorentz力量限制了场调节幅度为小于20克，以防止过量样品加热。 但是，许多HFHF-ESR线宽通常大于100克，因此希望开发替代现场调制。 通常，通常需要某种形式的信号编码才能具有可观察的信号。 我们目前正在探索使用光学圆形二色症（CD）光谱仪中常见的技术的可能性，并将其调整到HFHF-ESR光谱仪中，以在不使用磁场调制的情况下调节ESR共振。我们称为技术CD-ESR。 该技术依赖于以给定的参考频率交替用两个相对圆极化的光束来照明ESR样品。 在一个满足调制原理的所谓转移的圆极化状态的ESR样品中，ESR样品中有优先吸收。 最近的努力集中在开发具有两个圆形极化状态相等幅度的极化调节剂，以最大程度地减少仪器伪像。 我们最近对HFHF ESR光谱仪进行的升级将有助于实施此技术。 我们目前还研究了我们的CW来源170和240GHz的可能性，可以为实现必要的极化调制提供坚固而可靠的手段。 我们正在实施的修改后的反射桥足够灵活，以使我们可以直接地测试这些想法。