Spectroscopic Investigations of Vibrational Potential Energy Surfaces and Molecular Structures in Singlet and Triplet Electronic Excited States

近些年来，势能面(PESS)引起了人们的极大兴趣，尤其是电子激发态的势能面，因为它们可以提供关于分子结构、成键以及光化学和光物理过程的丰富数据。然而，根据振动数据严格确定的实验PESS很少被报道。几种不同的光谱方法将被用来绘制结构和构象重要振动的振动能级图。动能和势能计算方法将被应用于确定几种不同类型分子中几种电子激发态的PESS。对于单重态(通常为S1态)，喷冷分子的激光诱导荧光(LIF)光谱和紫外吸收光谱将被用来确定振动能级，而远红外和拉曼光谱将提供补充的基态数据。飞行时间质谱仪将用于电离检测和共振增强多光子电离(REMPI)研究。这将允许进入非荧光态和在单光子激光诱导荧光研究中被禁止的跃迁。将进行双色实验来研究更高的单线态。敏化磷光激发光谱(SPES)将被大量用于研究三重态。芳基酮将被彻底研究，因为这些分子显示出强烈的磷光，因此是三重态SPES研究的理想选择。我们还将研究吲哚分子的三重态和更高的单重态。为了确定电子跃迁对成键和结构的影响，还将在基态和激发态研究几种具有不寻常成键性质的分子，如反常效应。利用激光吸收光的光谱方法将被用来研究正常和激发态分子的结构和能量。当电子被光激发以获得更高的能量时，激发形式就会产生。光化学，如光合作用，通常只有在分子以这种方式被激发后才会发生。这项研究的目的是表征被激发的分子，并将它们与它们的正规形式进行比较。这项工作的结果可以证明对基于光与分子相互作用的各种领域是有益的，例如太阳能设备的开发或光化学反应的设计。学生和博士后研究助理将参与这项研究，并将接受培训，为进入科学/技术工作大军做好准备。

AbstractProposal : CHE-0131935PI : Laane, J. There has been great interest in potential energy surfaces (PESs) in recent years, particularly in those for electronic excited states, since they can provide a wealth of data on molecular structure, bonding, and photochemical and photophysical processes. However, very few experimental PESs, rigorously determined from vibronic data, have been reported. Several different spectroscopic methods will be used to map the vibronic energy levels for structurally and conformationally important vibrations. The computational methodology for kinetic and potential energy calculations will be applied to determine the PESs of several types of electronic excited states in several different kinds of molecules. For singlet states (generally S1) laser induced fluorescence (LIF) spectroscopy of jet-cooled molecules and ultraviolet absorption spectroscopy will be utilized to establish the vibronic levels while far-infrared and Raman spectra will provide the complementary ground state data. A time of flight mass spectrometer, which allows mass resolution, will be used for ionization detection and resonance enhanced multiphoton ionization (REMPI) studies. This will allow access to non-fluorescing states and to transitions forbidden in one-photon LIF studies. Two-color experiments will be carried out to study higher singlet states. Considerable use will be made of sensitized phosphorescence excitation spectroscopy (SPES) for studying triplet states. Aryl ketones will be thoroughly investigated as these molecules show strong phosphorescence and are thus ideal for SPES studies of triplet states. The triplet and higher singlet states for molecules in the indan family will also be investigated. Several molecules with unusual bonding properties, such as the anomeric effect, will also be studied in ground and excited states in order to ascertain the effect of the electronic transitions on the bonding and structure.Spectroscopic methods using lasers for the absorption of light will be used to study the structures and energies of molecules in both their normal and "excited" forms. The excited forms are produced when electrons are excited by light to attain higher energies. Photochemistry, such as photosynthesis, typically occurs only after molecules have been excited in this manner. The goal of this research is to characterize the excited molecules and to compare them to their normal forms. The results of this work can prove beneficial to a variety of areas based on the interaction of light with molecules, such as the development of solar energy devices or the design of photochemical reactions. Students and postdoctoral research associates will participate in this research and will receive training to prepare them for entry into the scientific/technical workforce.