Time-Resolved Structural Studies of Reacting Molecules Using Stroboscopic Gas Electron Diffraction Synchronous with Photoexcitation

使用与光激发同步的频闪气体电子衍射研究反应分子的时间分辨结构

• 批准号: 9616712
• 负责人: John Ewbank
• 金额: $ 11.7万
• 依托单位: University of Arkansas
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-01 至 1999-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9616712&HistoricalAwards=false
• 关键词: Time; Resolved; Structural; Studies; Reacting

In this project in the Physical Chemistry Program of the Chemistry Division, Professors J. Ewbank and L. Schafer of the Chemistry Department of the University of Arkansas will continue to apply stroboscopic diffraction techniques to the structural dynamics of chemical reactions. Laser-excited molecules in the vapor phase will be studied using time-resolved electron scattering in order to provide information about the time evolution of structures and vibrational probability distributions in reacting molecules. The time resolution will be extended down to the picosecond time domain and will be used to study UV-induced isomerizations of unsaturated organic compounds such as trans-stilbene, and structural and distribution dynamics following IR multiphoton absorption-induced processes such as intramolecular vibrational energy redistribution and dissociation reactions. Experimental observations of the structural kinetics of energized molecules in non-equilibrium distributions are an important chemical frontier which will stimulate advances in theory. Traditional gas electron diffraction (GED) has relied on the use of the photographic plate to record and store the information generated by the diffraction of electrons by molecules. This method was therefore limited to studying the structures of stable molecules. Current research in molecular dynamics concerns itself with how the structure and conformation of a molecular system evolves during a chemical reaction. Experimental information about such processes can be obtained only by means of techniques in which the time plays an essential role. The method of real-time GED developed by the principal investigators has shown great promise in making important contribution to the understanding of the properties of short-lived species. The aim of this project is to capitalize on this potential and contribute to our understanding of the basic aspects of molecular dynamics.

在化学系物理化学项目的这个项目中，J. Ewbank和L.阿肯色州大学化学系的谢弗将继续把频闪衍射技术应用于化学反应的结构动力学。 将使用时间分辨电子散射来研究气相中的激光激发分子，以便提供关于反应分子中的结构和振动概率分布的时间演化的信息。 时间分辨率将扩展到皮秒的时间域，并将用于研究紫外线诱导的异构化的不饱和有机化合物，如反式芪，和结构和分布动力学的红外多光子吸收诱导的过程，如分子内的振动能量重新分配和解离反应。 非平衡分布的能量分子的结构动力学的实验观察是一个重要的化学前沿，将刺激理论的进步。 传统的气体电子衍射（GED）依赖于使用照相底片来记录和存储由分子衍射电子所产生的信息。 因此，这种方法仅限于研究稳定分子的结构。 目前的分子动力学研究关注的是在化学反应过程中分子系统的结构和构象如何演变。 关于这些过程的实验信息只能通过时间起重要作用的技术手段来获得。由主要研究人员开发的实时GED方法在理解短寿命物种的特性方面做出了重要贡献。 这个项目的目的是利用这种潜力，并有助于我们了解分子动力学的基本方面。