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

Laane， J.近年来人们对势能面（PESs）产生了极大的兴趣，特别是电子激发态的势能面，因为它们可以提供丰富的分子结构、键合、光化学和光物理过程的数据。然而，很少有从振动数据严格确定的实验PESs的报道。几种不同的光谱方法将用于绘制结构和构象重要振动的振动能级。动力学和势能计算的计算方法将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（一般为S1），将利用射流冷却分子的激光诱导荧光光谱（LIF）和紫外吸收光谱来建立振动能级，而远红外光谱和拉曼光谱将提供互补的基态数据。飞行时间质谱仪，允许质量分辨率，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状态和在单光子LIF研究中禁止的跃迁。双色实验将用于研究更高的单重态。敏化磷光激发光谱（SPES）将在三重态研究中得到广泛应用。芳基酮将被彻底研究，因为这些分子表现出强烈的磷光，因此是理想的三态态的spe研究。在印度家族分子的三重态和更高的单线态也将被研究。为了确定电子跃迁对键和结构的影响，还将在基态和激发态研究一些具有特殊键性质的分子，如异头效应。利用激光吸收光的光谱学方法将被用于研究分子在正常和“受激”形式下的结构和能量。当电子被光激发以获得更高的能量时，就会产生激发态。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，并将它们与正常形式进行比较。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有益，例如太阳能装置的开发或光化学反应的设计。学生和博士后研究人员将参与这项研究，并将接受培训，为进入科学/技术劳动力做好准备。

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.