International Research Fellowship Program: Laser-Based Femtosecond X-Ray Development and Application

国际研究奖学金计划：基于激光的飞秒X射线开发和应用

• 批准号: 0502281
• 负责人: Rahul Shah
• 金额: --
• 依托单位: Shah Rahul C
• 依托单位国家: 美国
• 项目类别: Fellowship
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-06-01 至 2007-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0502281&HistoricalAwards=false
• 关键词: International; Research; Fellowship; Program; Laser

0502281ShahThe International Research Fellowship Program enables U.S. scientists and engineers to conduct three to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-two-month research fellowship by Dr. Rahul C. Shah to work with Dr. Antoine Rousse at the Laboratoire Optique Appliquee in Palaiseau, France.In a little over 100 years, x-rays have become one of the most powerful tools scientists have for peering into atomic scale structures. Among the various techniques, x-ray spectroscopy obviates the need for crystals, a requirement which severely limits range of studies for such atomic visualization. This work pushes x-ray science into dynamical studies of molecules at timescales of hundreds of femtoseconds by (1) developing an ultra-fast, directional, and broadband x-ray source from ultra-intense laser pulses and (2) utilizing it to identify femtosecond rearrangements in a chemical reaction by x-ray spectroscopy. The host site is where laser researchers have developed a 100 Terawatt, 10 Hz laser, and the work will be done in collaboration with Antoine Rousse and the Femtosecond X-ray Physics group, pioneers in the field of ultrafast x-ray source development and diffraction studies. The research more specifically studies the source spectrum by use of crystal spectrometer, and this is correlated with electron beam characteristics as well as plasma density, controlled by the density of the injected helium gas. Chemistry, biology, and solid state physics are all disciplines which have relied on x-rays for identification of molecular structures. Optical studies have indicated that systems in each of these disciplines evolve at femtosecond timescales but do not provide the structural details of x-rays. Thus this bright source of ultrafast x-rays which is of university laboratory scale stands to have far reaching impact. Demonstration of the usefulness of the source for quantitative x-ray absorption spectroscopy will introduce a valuable new tool, with advantages unique from diffraction techniques, to ultrafast x-ray studies.

0502281Shah国际研究奖学金计划使美国科学家和工程师能够在国外进行3至24个月的研究。该计划的奖项提供了联合研究的机会，并利用国外独特或互补的设施、专业知识和实验条件。该奖项将支持Rahul C.Shah博士与Antoine Rousse博士在法国帕莱索的Optique Appliquee实验室合作为期22个月的研究奖学金。在100多年的时间里，X射线已经成为科学家观察原子尺度结构的最强大的工具之一。在各种技术中，X射线光谱学消除了对晶体的需要，这一要求严重限制了这种原子可视化的研究范围。这项工作通过(1)从超强激光脉冲中开发出超快、定向和宽带的X射线源，以及(2)利用它通过X射线光谱学识别化学反应中的飞秒重排，将X射线科学推向了数百飞秒时间尺度上的分子动力学研究。主办地是激光研究人员开发出100太瓦、10赫兹激光器的地方，这项工作将与超快X射线源开发和衍射研究领域的先驱Antoine Rousse和飞秒X射线物理小组合作完成。本研究更具体地利用晶体光谱仪研究了源的光谱，这与电子束特性以及等离子体密度相关，受注入氦气体密度的控制。化学、生物学和固体物理学都是依靠X射线来鉴定分子结构的学科。光学研究表明，这些学科中的每一个系统都在飞秒时间尺度上演化，但没有提供X射线的结构细节。因此，这一大学实验室规模的超快X射线的明亮来源将产生深远的影响。证明定量X射线吸收光谱源的有用性，将为超快X射线研究引入一种有价值的新工具，具有衍射技术所独有的优势。