Vibrational Potential Energy Surfaces in Excited Electronic Singlet and Triplet States

在化学学部物理化学计划的这个项目中，德克萨斯理工大学的Jaan Laane教授将研究超音速冷却射流中分子电子激发态的振动势能面。荧光激发光谱和敏化磷光激发光谱将被记录为四，五，六元环化合物以及各种羰基和芳香分子。将对基态单线态、激发态单线态和三重态的势函数和构象进行比较。从头计算也将进行，以帮助提供更好的理论基础，以理解由电子激发引起的变化。对非刚性分子的大振幅振动运动的研究提供了控制这些软性分子构象变化的力和能量的信息，即从一种“稳定”结构到另一种“稳定”结构的变化。这个信息可以用一个叫做势能面的数学函数来描述。这些研究还提供了一种结构转化为另一种结构并再转化为另一种结构的速率的信息。这个项目将收集关于几种类型的非刚性环分子的势能面信息，强调当分子被提供足够的能量来激发电子到更高的能量状态时，表面发生的变化。还将进行计算，为理解电子激发引起的结构和势能变化提供理论基础。

In this project in the Physical Chemistry Program of the Chemistry Division, Professor Jaan Laane of Texas A. and M. University will study vibrational potential energy surfaces in electronically excited states of molecules in a supersonically cooled jet. Fluorescence excitation spectra and sensitized phosphorescence excitation spectra will be recorded for four-, five-, and six-membered ring compounds as well as for various carbonyl and aromatic molecules. A comparison with potential functions and conformations for ground singlet and excited singlet and triplet states will be made. Ab initio calculations will also be carried out to help provide a better theoretical basis for understanding the changes resulting from electronic excitation. %%% The study of large-amplitude vibrational motions of non-rigid molecules provides information about the forces and energies which govern the conformational changes in these floppy molecules, that is, the changes from one "stable" structure to another "stable" structure. This information can be described by a mathematical function called a potential energy surface. Information about the rate at which one structure will convert to another and back again is also provided by such studies. This project will gather information about potential energy surfaces of several types of non-rigid ring molecules, emphasizing the changes in the surfaces that occur when the molecule is supplied enough energy to excite an electron to higher energy states. Calculations will also be carried out to provide a theoretical basis for understanding the structural and potential energy changes resulting from electronic excitation.