Structural Kinetics, a Novel Tool Using Gas Electron Diffraction With a Pulsed Electron Beam Synchronous With Photoexcitation

结构动力学，一种利用气体电子衍射和与光激发同步的脉冲电子束的新型工具

• 批准号: 9314064
• 负责人: John Ewbank
• 金额: $ 25.34万
• 依托单位: University of Arkansas
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-01-01 至 1996-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9314064&HistoricalAwards=false
• 关键词: Structural; Kinetics; Novel; Tool; Using

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 the development and application of real-time gas electron diffraction (GED) using a pulsed electron beam synchronous with photoexcitation. The technique will be applied primarily to the study of the conformation and structure of short-lived chemical species, namely those in highly excited electronic states where the structure and conformation differ significantly from those in the ground and low-lying excited states, or species undergoing dynamical changes as the result of unimolecular reactions. Traditional 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 reaction process. Experimental information about such processes can only be obtained by means of techniques in which the time plays an essential role. The methods of pico- and femtosecond spectroscopy have been very successful in this regard but also have their limitations owing to the difficulty in interpreting often extremely complex spectral patterns. 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.

在化学系物理化学计划的这个项目中，阿肯色大学化学系的J.Ewbank和L.Schafer教授将继续开发和应用与光激发同步的脉冲电子束的实时气体电子衍射(GED)。这项技术将主要用于研究短寿命化学物种的构象和结构，即处于高激发态的化学物种，其结构和构象与基态和低激发态显著不同，或由于单分子反应而发生动力学变化的物种。传统的GED一直依赖于使用照相底片来记录和存储分子对电子的衍射产生的信息。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分子体系的结构和构象在反应过程中如何演变。关于这种过程的实验信息只能通过时间起关键作用的技术手段获得。皮秒和飞秒光谱学方法在这方面非常成功，但也有其局限性，因为很难解释往往极其复杂的光谱模式。由主要研究人员开发的实时GED方法在理解短生命物种的性质方面显示出巨大的潜力。这个项目的目的是利用这一潜力，并有助于我们理解分子动力学的基本方面。