Spectroscopic Determinations of Excited State Properties of Organometallic and Inorganic Compounds

无机、生物无机和有机金属化学项目支持无机光化学的基础研究。该项目处于该领域的前沿，有潜力以多种方式造福社会：催化、光学和光电设备以及能量的光转换。提出的研究计划是对有机金属化合物，特别是金属碳、碳炔、烯烃和亚硝基化合物的电子激发态进行三重研究。第一组实验是利用单晶偏振光谱对激发态进行赋值。新的实验技术使得在低温下测量晶体中取向分子具有高消光系数的吸收带成为可能。详细的作业将被分配。当存在振动结构时，将用于确定激发态畸变。另一个结果是金属-配体相互作用的定量实验测量，将与配体场和分子轨道理论进行比较。该计划的第二个组成部分是利用预共振拉曼光谱，电子光谱和时间相关理论的组合来确定激发态畸变。这种组合使得计算激发态电位超表面沿正模的所有畸变的大小成为可能。第三组实验是利用激发态泵浦探测拉曼光谱测量激发态分子的几何形状。在这些实验中，激发态是由一个光子的吸收产生的，在这个激发态中分子的振动光谱是用第二个光子的拉曼光谱测量的。这种方法是对上述技术的补充，对于研究极大的畸变和亚稳中间体特别有用。这三组实验的目标是统一理解激发态轨道特性、潜在表面位移和有机金属的激发态几何形状。

The Inorganic, Bioinorganic and Organometallic Chemistry Program supports basic research in inorganic photochemistry. This project is at the forefront of an area with the potential to benefit society in numerous ways: catalysis, optical and electro-optical devices and photoconversion of energy. The proposed research program is a three-fold investigation of the electronic excited states of organometallic compounds, especially metal carbene, carbyne, olefin and nitrosyl compounds. The first group of experiments is the assignment of excited states by using single crystal polarized spectroscopy. New experimental techniques make it possible to measure absorption bands with high extinction coefficients of oriented molecules in crystals at low temperatures. Detailed assignments will be made. Vibronic structure, when present, will be used to determine the excited state distortions. An additional result is the quantitative experimental measurement of metal-ligand sigma and pi interactions which will be compared with both ligand field and molecular orbital theory. The second component of the program is the determination of excited state distortions by using a combination of pre-resonance Raman spectra, electronic spectra and time-dependent theory. This combination makes it possible to calculate the magnitudes of all of the distortions along normal modes in the excited state potential hypersurface. The third group of experiments is the measurement of geometries of molecules in excited electronic states by using excited state pump-probe Raman spectroscopy. In these experiments, excited states are produced by absorption of one photon and the vibrational spectrum of the molecule in this excited state is measured by Raman spectroscopy with a second photon. This method is complementary to the above techniques and will be especially useful for studying extremely large distortions and metastable intermediates. The goal of the three groups of experiments is the unified understanding of excited state obital characteristics, potential surface displacements, and excited state geometries of organometallics.