A Compact Laser Excited Coherent X-ray Source for Macromolecular Imaging

用于高分子成像的紧凑型激光激发相干 X 射线源

• 批准号: 9513266
• 负责人: W. Andreas Schroeder
• 金额: $ 6万
• 依托单位: University of Illinois at Chicago
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-04-15 至 1997-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9513266&HistoricalAwards=false
• 关键词: Compact; Laser; Excited; Coherent; ray

This proposal outlines a three year program to develop a compact coherent X-ray source that is suitable for three-dimensional imaging of living organisms, tissue and cells with macromolecular resolution. The imaging is to be accomplished using X-ray rnicroholographic techniques. The X-rays will be produced by exciting atornic clusters or molecules with an intense ultrashort (femtosecond) laser pulse in the ultraviolet (UV). The resulting multiphoton ionization of the atoms in the clusters produces an electron-ion plasma which interacts strongly with the oscillating radiative field of the laser pulse. The collective motion of the electrons, due to the field-induced ponderomotive force, gives the electrons sufficient energy to collisionally eject an inner-shell electron from an ion in the cluster. A X-ray photon is emitted when an outer shell electron fills the vacant inner shell state in the "hollow" atom. Previous investigations have shown that the efficiency of this nonlinear X-ray generation process is increased if the interacting laser pulse is both intense (i.e. short and energetic) and coherent (i.e. phase controlled). We describe an all solid-state, high-power UV femtosecond laser system that is designed to be optimally suited for the excitation of atomic clusters for the production of X-rays. The laser system will be based on the new solid-state UV laser material Ce doped LiSrAlF6 which operates between 280 and 320nm, and will employ femtosecond laser technology that is already well established at wavelengths in the near infrared (~ 800nm). In addition to its use in the X-ray generation process, we expect this source of coherent UV femtosecond pulses to find many applications in spectroscopic biological research, e.g. the temporal resolution of the water solvation dynamics in enzyme reactions and other protein complexes. We intend to use the coherent X-ray source produced using the UV laser system to image chromosome dynamics during mitosis and meio sis. The microholographic techniques that have already been developed in our laboratories will enable three dimensional images to be reconstructed, in contrast to any other imaging technology available today with comparable marcomolecular resolution. Using X-rays with a wavelength of -l, this holographic technique should also allow the structure of biological molecules to be visualized in three dimensions without the need for crystallization. We propose to explore this possibility by investigating the avidin-biotin complex. The development of this laser-based technology has the potential to replace expensive synchrotron X-ray sources for imaging in the biological sciences.

该提案概述了一项为期三年的计划，以开发一种紧凑的相干X射线源，适用于具有大分子分辨率的活生物体，组织和细胞的三维成像。成像将使用X射线显微全息技术完成。X射线将通过用紫外线（UV）中的强烈超短（飞秒）激光脉冲激发原子团簇或分子来产生。由此产生的多光子电离的原子在集群中产生的电子离子等离子体强烈相互作用的振荡辐射场的激光脉冲。由于场致有质动力，电子的集体运动给予电子足够的能量，使其从团簇中的离子中碰撞射出内壳层电子。当外层电子填充“空心”原子中的空的内壳层状态时，X射线光子被发射。先前的研究表明，如果相互作用的激光脉冲既强（即短且高能）又相干（即相位受控），则这种非线性X射线产生过程的效率会增加。 我们描述了一个全固态，高功率紫外飞秒激光系统，设计为最适合于激发原子团簇的X射线的生产。 该激光系统将基于新型固态紫外激光材料Ce掺杂LiSrAlF 6，其工作波长在280至320 nm之间，并将采用飞秒激光技术，该技术已经在近红外波长（~ 800 nm）建立。除了在X射线产生过程中的应用外，我们还希望这种相干紫外飞秒脉冲源在光谱生物学研究中有许多应用，例如酶反应和其他蛋白质复合物中水溶剂化动力学的时间分辨率。 我们打算使用相干X射线源产生的紫外激光系统的图像染色体动态有丝分裂和减数分裂。显微全息技术已经在我们的实验室开发，将使三维图像被重建，与任何其他成像技术相比，今天可用的具有可比的大分子分辨率。使用波长为-1的X射线，这种全息技术还可以使生物分子的结构在三维空间中可视化，而不需要结晶。我们建议通过研究抗生物素蛋白-生物素复合物来探索这种可能性。这种基于激光的技术的发展有可能取代昂贵的同步加速器X射线源，用于生物科学中的成像。