Studies of Olefin Triplets and Triplet Biradicals

本项目将探讨烯烃三重态和三重双自由基形成和衰变的热力学和动力学因素。通过将传统的光化学技术，如产物分析和量子产率测量与激光闪光和时间分辨光声量热法相结合，将出现对三重态光化学过程的完整描述。将实验结果与理论计算相结合，对系统间交叉及其所涉及的能量面进行全面而基本的分析。这项研究的一个重要成果将是更好地了解双基化合物，并提出新的生产方法。这项研究将为从三重态表面到基态表面的系统间交叉以及控制这些过程的因素（如自旋-轨道耦合）提供关键和确定的理论。这项来自有机动力学项目的资助用于支持德克萨斯大学达拉斯分校Richard A. Caldwell教授的继续工作。这些研究将探讨发生在化学过程中的中间态的基本性质。通过测量这些中间物质吸收光的方式，以及它们形成和衰变过程中所涉及的热量，就有可能预测其他类似（有时不太相似）的过程将如何进行。这些基础知识是通过使用特殊设计的仪器获得的，这些仪器能够记录十亿分之一秒发生的现象，将与计算机计算的理论预测相结合，提供通过使用光能将一种分子转化为另一种分子所需能量的完整描述。所获得的信息在利用光引起快速而有效的变化的各种应用中是有用的，例如在计算机芯片处理过程中发生的变化。

This project will probe both the thermodynamic and kinetic factors involved in the formation and decay of alkene triplet states and triplet biradicals. By combining conventional photochemical techniques such as product analysis and quantum yield measurements with laser flash and time resolved photoacoustic calorimetry, a complete decription of triplet state photochemical processes will emerge. By combining the experimental results with theoretical calculations, a thorough and fundamental analysis of intersystem crossing and the corresponding energy surfaces involved will be developed. An important outcome of the investigation will be a better understanding of biradicals, and new methods for their production will be suggested. The investigation will provide critical and definitive conformation of theories for intersystem crossing from triplet to ground state surfaces and the factors, such as spin-orbit coupling, which control these processes. %%% This grant from the Organic Dynamics Program supports the continuing work of Professsor Richard A. Caldwell at The University of Texas at Dallas. These studies will probe the basic nature of the intermediate states which occur in chemical processes. By measuring the way that these intermediate species absorb light and how much heat is involved in their formation and decay, it is possible to predict how other similar, and in some cases not so similar, processes will proceed. Such fundamental knowledge, which is obtained by using specially designed instruments which are able to record phenomena which occur on the order of billionths of a second, will be combined with the theoretical predictions from computer calculations to provide a complete description of the energy requirements for converting one molecule into another via the use of light energy. The information gained will be useful in a variety of applications which use light to induce rapid and efficient changes, such as those which occur during the processing of computer chips.