Vibrational Potential Energy Surfaces and Molecular Structures In Electronic Excited States

实验物理化学计划支持德克萨斯A&M大学的Jaan Laane教授继续研究具有大振幅振动的分子。他将使用荧光激发光谱、敏化磷光激发光谱和带有光子或电离检测的双光子光谱来绘制激发态的能级。他将专注于环状和多环的羰基化合物和芳香族分子，特别是那些具有两个生色团和紧密电子态的分子，或者那些表现出有趣的结构变化的分子，如光异构化或光异构化。LAANE还将使用分散荧光、远红外和拉曼光谱来获得基态表面的补充信息，并使用分子力学(MM3)和从头计算来预测势能面和结构。更好地理解电子激发态对于更好地了解光化学和其他重要的化学过程以及一般的化学键和结构是很重要的。确定激发态的势能面将提供对与这些态相关的能量学和相互作用的详细了解。将在这里进行的实验工作将提供计算势能面所需的数据，并将有助于进一步改进我们收集这类光谱信息的实验程序。关于三重态分子或在吸收后发生有趣的结构变化的分子的结果应该提供过去不容易获得的基本信息。

The Experimental Physical Chemistry Program supports Prof. Jaan Laane of Texas A&M University in his continuing studies of molecules with large-amplitude vibrations. He will use fluorescence excitation spectroscopy, sensitized phosphorescence excitation spectroscopy and two-photon spectroscopy with photon or ionization detection to map the energy levels of the excited states. He will focus on cyclic and multicyclic carbonyl compounds and aromatic molecules, especially those molecules with two chromophores and closely lying electronic states or those molecules exhibiting interesting structural changes such as photoracemization or photoisomerization. Laane will also use dispersed fluorescence and far-IR and Raman spectroscopies to obtain complementary information on the ground state surfaces, and molecular mechanics (MM3) and ab initio calculations to predict potential energy surfaces and structures. An improved understanding of electronic excited states is important for providing a better perspective of photochemical and other important chemical processes as well as on chemical bonding and structure in general. Determination of the potential energy surfaces for the excited states will provide detailed insight into the energetics and interactions associated with these states. The experimental work to be carried out here will provide the data necessary for calculating the potential energy surfaces and will also further help improve our experimental procedures for collecting this type of spectroscopic information. Results on molecules in triplet states or on molecules that undergo interesting structural changes upon absorption should provide fundamental information that has not been readily attained in the past.