Excimer Laser System for Pump-Probe Experiments

一个准分子激光系统将被购买并用于支持乔治华盛顿大学在燃烧化学、材料加工和化学分析方面的几个既定研究项目。这些项目包括合成金刚石薄膜形成中的激光-固体相互作用，用于化学分析的玻璃和陶瓷靶材的激光取样，燃烧过程中重要的自由基物种的激光产生，以及氯代烃的光解离。在前两个区域，目标将是跟踪在表面和大部分目标内发生的变化，并检查产生的羽流的特性。研究方法将包括飞行时间质谱仪、产生的离子的动能测量以及羽流中颗粒的分析。此外，还将从理论上研究各种激光和选定材料的激光-固体相互作用。在第三个领域，将使用准分子激光光解来制备燃烧系统中重要的自由基物种。然后将使用现有的可调谐半导体激光光谱仪获得这些物种的吸收光谱。还将探索使用准分子激光光解和红外吸收来诊断实验室规模的扩散火焰中的氯代烃。前两项活动的总体目标是加强对激光-固体相互作用的了解，并将这一知识用于准备和分析应用。这将包括激光取样和脉冲激光沉积过程的优化。此外，更好地了解人造钻石的形成是一个目标。在后一种活动中，准分子激光光解已成为制备一些基础光谱研究的气相自由基物种的首选技术。此外，还提出了氯代烃的准分子激光光解也可用于检测不良燃烧产物。

An Excimer Laser System will be purchased and used to support several established research programs in combustion chemistry, materials processing , and chemical analysis at George Washington University. These programs include laser-solid interaction in synthetic diamond film formation, laser sampling of glass and ceramic targets for chemical analysis, laser production of radical species important in combustion processes, and photodissociation of chlorinated hydrocarbons. In the first two areas, the goal will be to follow changes occurring on the surface and within the bulk of the targets and to examine the properties of the generated plumes. Methods of investigation will include time-of-flight mass spectrometry, kinetic energy measurement of the ions produced, and analysis of particulates in the plumes. In addition, laser-solid interactions will be examined theoretically for a broad range of lasers and selected materials. In the third area, excimer laser photolysis will be used to prepare radical species which are important in combustion systems. Absorption spectra for these species will then be obtained using an existing tunable diode laser spectrometer. Use of excimer laser photolysis followed by IR absorption as a diagnostic for chlorinated hydrocarbons in lab scale diffusion flames will also be explored. The general objectives of the first two activities are to enhance the understanding of laser-solid interactions and to use this knowledge in preparative and analytical applications. This will include optimization of laser sampling and pulsed laser deposition processes. In addition, a better understanding of synthetic diamond formation is a goal. In the latter activities, excimer laser photolysis has become the technique of choice for the preparation of a number of gas phase radical species for fundamental spectroscopic studies. Additionally, it is proposed that excimer laser photolysis of chlorinated hydrocarbons might also be used for the detection of undesirable combustion products.