Ultraviolet Surface Photodynamics and Photochemistry

紫外表面光动力学和光化学

• 批准号: 8803390
• 负责人: Richard Martin
• 金额: --
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-06-15 至 1992-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8803390&HistoricalAwards=false
• 关键词: Ultraviolet; Surface; Photodynamics; Photochemistry

This project is in the general area of analytical and surface chemistry and in the subfields of photochemistry and surface reaction dynamics. The research continues the Principal Investigator's studies of the photofragmentation, via internally repulsive states excited by an ultraviolet laser, of molecules adsorbed on metal and semiconductor surfaces. Photofragmentation, which generates radicals important in surface reactions, can proceed on these surfaces even in the presence of very fast (250 - 2500 femtoseconds) quenching of the excited states by energy transfer to the substrate. The role of faster charge transfer processes (5 - 50 fs) will be investigated by measuring the cross- sections, photofragment velocity and angular distributions, and polarization dependence for a series of small adsorbate molecules. Ultraviolet laser surface photochemistry is an important new area of fundamental research which has potentially broad applications in diverse technological fields such as semiconductor processing, solar energy conversion, chemical catalysis, and eye surgery. However, little is known about the fundamental mechanisms underlying the photochemical reactions. Both charge transfer and electron attachment have been identified as important reaction channels. Studies of the photofragmentation of adsorbed molecules will provide a highly specific probe of the dynamics of energy and charge transfer at interfaces.

这个项目属于分析化学和表面化学的一般领域，以及光化学和表面反应动力学的子领域。该研究继续了首席研究员的光碎裂研究，通过紫外激光激发的内部排斥状态，分子吸附在金属和半导体表面。光碎裂，在表面反应中产生重要的自由基，可以在这些表面上进行，即使存在非常快（250 - 2500飞秒）的激发态被转移到衬底的能量猝灭。快速电荷转移过程（5 - 50fs）的作用将通过测量一系列小吸附分子的横截面、光碎片速度和角分布以及偏振依赖性来研究。紫外激光表面光化学是一门重要的基础研究新领域，在半导体加工、太阳能转换、化学催化、眼科手术等技术领域具有广阔的应用前景。然而，人们对光化学反应的基本机制知之甚少。电荷转移和电子附着都是重要的反应通道。对吸附分子的光破碎的研究将为界面上能量和电荷转移的动力学提供一个高度特异性的探针。