Enhancement of the Undergraduate Physical Chemistry Laboratory: A Versatile and Novel Pulsed Laser-Based System for Nanosecond Time-Resolved Luminescence Studies in Molecular Phot

本科生物理化学实验室的增强：用于分子光纳秒时间分辨发光研究的多功能新型脉冲激光系统

• 批准号: 9952604
• 负责人: Ramaswami Viswanathan
• 金额: $ 3.57万
• 依托单位: Beloit College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-03-01 至 2003-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9952604&HistoricalAwards=false
• 关键词: Enhancement; Undergraduate; Physical; Chemistry; Laboratory

Chemistry (12) Ultrashort laser pulse-based experiments have become ubiquitous in experimental physical chemistry. In order for students to understand recent developments and obtain "hands on" experience with such techniques, access to a pulsed laser-based system with pump-probe capability for luminescence studies is important. In this project, the instrumentation to do this is being incorporated into the undergraduate physical chemistry laboratory curriculum. The system consists of a Q-Switched YAG laser with harmonic generation in either the near-UV (355 nm) or mid-UV (266 nm) with a 3 ns (4-8 mJ) pulse, thus providing excitation in a variety of molecules. The fast luminescence is detected by a sensitive PIN photodiode detector with 400 ps response and digitized by an ultrahigh bandwidth (1 GHz) digital oscilloscope. The YAG laser is also used to pump an existing tunable dye laser, whose probe output is temporally delayed from 0 to 50 ns using an inexpensive and novel optical delay line based on a toy train track and engine. A set of experiments for the undergraduate physical chemistry laboratory that measure fluorescence lifetimes of a series of aromatic hydrocarbons and also directly monitor intersystem crossing processes on the nanosecond time scale using optically delayed triplet- triplet absorption are being adapted and implemented, with enhancements. The adapted materials come from both the chemical education literature (J. Chemical Education) and from the research literature. The laser equipment is also being introduced into inorganic, organic and advanced organic courses, courses not normally associated with laser chemistry. This considerably broadens the impact of this project. Evaluation and assessment activities are being assisted by an external evaluator, experienced in laser chemistry, and by a chemical education specialist. The results will be disseminated through dedicated Web pages and papers submitted to the Journal of Chemical Education.

基于超短激光脉冲的实验在实验物理化学中已变得无处不在。为了让学生了解最近的发展并获得此类技术的“实践”经验，获得具有泵浦-探测能力的基于脉冲激光的系统以进行发光研究是重要的。在这个项目中，这样做的仪器正在被纳入本科生的物理化学实验课程。该系统由调Q的YAG激光器组成，在近紫外光(355 Nm)和中紫外光(266 Nm)处产生谐波，脉冲宽度为3 ns(4-8mJ)，从而在各种分子中提供激发。快速发光由响应为400ps的灵敏PIN光电二极管探测器探测，并由超高带宽(1 GHz)数字示波器数字化。该激光器还被用来泵浦现有的可调谐染料激光器，其探测输出被时间延迟从0到50 ns，使用基于玩具火车轨道和发动机的廉价且新颖的光学延迟线。正在调整和实施本科生物理化学实验室的一系列实验，这些实验测量一系列芳香烃的荧光寿命，并使用光学延迟的三重态-三重态吸收在纳秒时间尺度上直接监测系间交叉过程，并进行了改进。改编的材料来自化学教育文献(J.化学教育)和研究文献。激光设备也被引入到无机、有机和高级有机课程中，这些课程通常与激光化学无关。这大大扩大了该项目的影响。评价和评估活动得到一名在激光化学方面有经验的外部评估员和一名化学教育专家的协助。结果将通过专门的网页和提交给《化学教育杂志》的论文进行传播。