Advanced X-ray Spectroscopy for Biological Chemistry

用于生物化学的先进 X 射线光谱

• 批准号: RGPIN-2019-05351
• 负责人: George, Graham
• 金额: $ 3.5万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=738214
• 关键词: Advanced; ray; Spectroscopy; Biological; Chemistry

X-ray absorption spectroscopy (XAS) uses synchrotron radiation to probe the electronic structure and physical arrangement of other atoms around a target element in almost any matrix. While XAS is well-established, bringing important insights in a range of disciplines, like any method it has inherent limitations that curb its utility. In this proposal I lay out plans to push the boundaries of this important synchrotron technique and to make these advances available to the wider research community. Four limitations of XAS include: (1) poor bond-length resolution; (2) little or no geometrical information; (3) poor spectroscopic resolution; and (4) lack of access to very low concentrations. My previous work explored methods of overcoming limitations (1) and (2); here I focus on addressing limitations (3) and (4), through a suite of methods known collectively as advanced X-ray spectroscopy (AXS). AXS methods are photon-in/photon-out spectroscopies, where both incident and emitted photons are measured with very high energy resolution. The so-called high energy resolution fluorescence detection (HERFD) overcomes the inherent broadening of the spectra, which is due to the lifetime of the core-hole created when an electron is excited. Instead HERFD is sensitive to the much longer lifetime of the core-hole created upon emission. The exquisitely sharper spectra that result from HERFD allow greater sensitivity to speciation of chemical forms and studies of electronic structure. At the same time, the enormously improved background rejection allows access to the ultra-dilute concentration regime - an unusual spectroscopic win-win! OBJECTIVES AND SCIENTIFIC APPROACH: I seek to develop AXS methodology in both tender (2-5 keV) and hard (>5keV) X-ray energy regimes, moving it from a highly-specialized to a mainstream technique. I achieve this through targeted research projects using AXS in my career interests of bioinorganic and biological chemistry. These include studies of elements essential for life such as Mo, W, and Cu; and of toxic elements such as As and Hg, and their relationship with the essential element Se. NOVELTY AND EXPECTED SIGNIFICANCE: The opportunities afforded by AXS are no less than revolutionary, poised to transform the use of XAS in environmental and health science, amongst many other disciplines. Since AXS facilities are now emerging at synchrotron facilities worldwide, our proposed work will position the Canadian community to be among the world leaders in this area, and provide unparalleled opportunities for cross-disciplinary training of highly qualified personnel at the forefront of synchrotron technique development.

X射线吸收光谱（XAS）使用同步辐射来探测几乎任何基质中目标元素周围其他原子的电子结构和物理排列。虽然XAS是成熟的，在一系列学科中带来了重要的见解，但像任何方法一样，它具有固有的局限性，限制了其实用性。在这份提案中，我提出了一些计划，以推动这一重要的同步加速器技术的边界，并使这些进步可用于更广泛的研究社区。 XAS的四个局限性包括：（1）差的键长分辨率;（2）很少或没有几何信息;（3）差的光谱分辨率;和（4）无法获得非常低的浓度。我以前的工作探索了克服限制（1）和（2）的方法;在这里，我专注于解决限制（3）和（4），通过一套统称为先进X射线光谱学（AXS）的方法。AXS方法是光子输入/光子输出光谱法，其中入射和发射光子都以非常高的能量分辨率测量。所谓的高能量分辨率荧光检测（HERFD）克服了光谱的固有加宽，这是由于当电子被激发时产生的核心空穴的寿命。相反，HERFD对发射时产生的芯空穴的更长寿命敏感。由HERFD产生的非常清晰的光谱使得对化学形式的物种形成和电子结构的研究具有更高的灵敏度。同时，大大提高的背景抑制允许进入超稀浓度制度-一个不寻常的光谱双赢！ 目标和科学方法：我寻求在弱（2-5 keV）和硬（> 5 keV）X射线能量范围内开发AXS方法，将其从高度专业化的技术转变为主流技术。我通过有针对性的研究项目使用AXS在我的职业兴趣的生物无机和生物化学实现这一点。这些研究包括对生命必需元素如Mo、W和Cu的研究，以及对有毒元素如As和Hg的研究，以及它们与必需元素Se的关系。 新奇和预期意义：AXS提供的机会不亚于革命性的，准备改变XAS在环境和健康科学以及许多其他学科中的使用。由于AXS设施现在出现在世界各地的同步加速器设施，我们提出的工作将定位加拿大社区在这一领域的世界领导者之一，并提供无与伦比的机会，跨学科的高素质人才的培训，在同步加速器技术发展的最前沿。