RUI: Spectroscopic Studies of Cyclic Conjugated Molecules in Triplet (n,pi*) Excited States

在这个由化学系实验物理化学计划资助的项目中，斯蒂芬·德鲁克教授和他在威斯康星大学欧克莱尔分校的本科生将继续他们对处于三重态激发态的有机小分子的光谱研究。三重态(具有两个未配对电子的物种)在许多光化学反应中起着核心作用。德鲁克教授和他的团队一直在研究一系列环状共轭烯酮分子的最低三重态。他们探索了三重态和单重态之间的结构和动力学差异。除了这类研究提供的基本见解外，这些实验还提供了基准光谱信息，用于测试或改进激发态及其所介导的光化学过程的计算处理。在这项拟议的研究中，学生们将使用敏感的光谱技术--腔振铃吸收和磷光激发--来确定三重态中C=O和C=C伸缩振动的频率。这些数据将补充该小组以前获得的关于环烯酮的低频环振动的信息。研究人员还将扩大他们的工作范围，将内酯和类似于烯酮的酸酐分子包括在内。到目前为止，从室温光谱获得的信息一直受到由于热带造成的光谱拥堵的限制。为了消除热带，德鲁克教授的团队建议使用狭缝喷嘴源记录喷射冷却条件下的空腔振荡谱。在这个项目中，本科生小组成员将进行深入的研究。这样的机会为本科教育项目增加了实质性的价值，也可以培养丰富的深造机会。正在进行的合作(与普渡大学、德克萨斯农工大学和南加州大学的研究人员)将使德鲁克教授的本科生能够参与一系列活动。反过来，合作研究小组的研究生将能够在与德鲁克教授和他来自威斯康星大学克莱尔分校的学生互动时，探索本科院校的教师职业生涯。

In this project, funded by the Experimental Physical Chemistry Program of the Chemistry Division, Prof. Stephen Drucker and his undergraduate students at the University of Wisconsin-Eau Claire will continue their spectroscopic studies of small organic molecules in triplet excited states. Triplet states (species having two unpaired electrons) play a central role in many photochemical reactions. Prof. Drucker and his group have been investigating the lowest triplet states of a series of cyclic conjugated enone molecules. They have explored structural and dynamical differences between the triplet states and their singlet counterparts. Beyond the fundamental insights offered by such investigation, the experiments provide benchmark spectroscopic information for testing or refining computational treatments of excited states and the photochemical processes they mediate. In the proposed research, students will use sensitive spectroscopic techniques - cavity ringdown absorption and phosphorescence excitation - to determine frequencies of the C=O and C=C stretching vibrations in the triplet states. The data will complement information that the group obtained previously on low-frequency ring vibrations of the cyclic enones. The researchers will also extend their work to include lactone and anhydride molecules analogous to the enones. Heretofore, the information available from the room temperature spectra has been limited by spectral congestion due to hot bands. To eliminate the hot bands, Prof. Drucker's group proposes to record the cavity ringdown spectra under jet-cooled conditions using a slit nozzle source. In this project, undergraduate group members will conduct in-depth research. Such opportunities add substantial value to the undergraduate education program, and can also foster rich opportunities for advanced study. Ongoing collaborations (with investigators at Purdue, Texas A&M, and USC) will enable Prof. Drucker's undergraduates to participate in a range of activities. In turn, graduate students in the collaborating research groups will be able to explore faculty careers at undergraduate institutions as they interact with Prof. Drucker and his students from UW-Eau Claire.