Ultrafast time-resolved studies of reactive intermediates

在有机和高分子计划的支持下，Matthew Platz教授和他的团队计划研究重氮、重氮化合物和叠氮化物(“前体”)的光化学，以及卡宾和硝化反应中间体的诞生。利用飞秒时间分辨的UV-Vis和IR光谱以及计算方法，他们将了解到前体分子的哪个跃迁被泵浦，以及前体的哪个激发态导致碎裂，形成活性中间体和氮。如果泵浦状态和解离状态不同，他们将研究连接它们的路径和解离过程的时间尺度。他们将验证重排可以与氮气挤出协同进行，并确定负责这一过程的激发态。他们将监测热反应中间体的形成，以及控制它们向溶剂传递热量的速度的结构和环境因素，以及它们是否在松弛时重新排列。该小组将学习单重态反应中间体的寿命以及控制其松弛为三重态物种的因素。这项研究有几个广泛的影响。学生接受经典有机化学以及超快光谱技术和先进计算方法的培训。学生将学习在合成化学、分析化学、超快光谱学和理论方面的小组工作。有机化学家、分析化学家和物理化学家一起工作，相互学习。从历史上看，Platz实验室欢迎女性、少数族裔和大多数高中生实习生、本科生、研究生、博士后和访问教职员工。学生学习与不同种族、民族、国籍和教育水平的人合作。该实验室的许多毕业生被安排在大学、学院和高中教授化学，他们致力于延续这一传统。

With the support of the Organic and Macromolecular Program, Professor Matthew Platz and his group plan to study the photochemistry of diazirines, diazo compounds and azides ("precursors") and the birth of carbenes and nitrene reactive intermediates. Using femtosecond time resolved UV-Vis and IR spectroscopy and computational methods they will learn which transition of the precursor molecules is pumped and which excited state of the precursor leads to fragmentation to form a reactive intermediate and nitrogen. If the pumped state and dissociative states are not the same, they will study the pathway connecting them and the time scale of the dissociative process. They will verify that rearrangement can proceed in concert with nitrogen extrusion and identify the excited state responsible for that process. They will monitor the formation of hot reactive intermediates and the structural and environmental factors that control the rate at which they transfer heat to solvent and if they rearrange as they relax. The group will learn the lifetime of singlet reactive intermediates and the factors that control their relaxation to triplet state species. The research has several broad impacts. Students are trained in classical organic chemistry as well as ultrafast spectroscopic techniques and advanced computational methods. Students will learn to work in a group that does synthetic chemistry, analytical chemistry, ultrafast spectroscopy and theory. Organic, analytical and physical chemists work together and learn from each other. Historically, the Platz Laboratory welcomes women, minority and majority high school student interns, undergraduates, graduate students, post doctoral students and visiting faculty. Students learn to work with individuals of many races, ethnicities, nationalities and educational level. Numerous graduates of the laboratory have been placed in university, college and high school positions teaching chemistry, and they are committed to continue this tradition.