Nonlinear Raman Spectroscopy of Intermolecular Vibrations in Molecular Clusters

Felker得到了实验物理化学计划的支持，继续他的基态光谱研究，分离的中性分子簇，使用在他的实验室开发的质量选择，电离检测受激拉曼光谱（IDSRS）技术。这些研究的重点是表征中性团簇的分子间振动水平结构，主要目的是获得有关分子间势能面和集体振动模式的信息。研究的体系包括(1)氢键二聚体，包括与水或氨的芳烃，以及水二聚体；(2)较大的氢键和均相芳香团簇；(3)自由基及其与稀有气体原子和小分子的配合物。该项目还包括模拟分子间拉曼光谱的计算工作，以方便观察波段的分配和从实验结果中提取分子间电位参数。这项研究计划的总体目标是推进有关分子如何相互作用的知识状态。这些研究的结果预计将影响凝聚态系统计算机建模中使用的力场的发展，包括生物学上重要的分子、吸附在表面上的分子和用于技术应用的新材料。特别是发现水基簇的详细性质，可能对改善对环境和生化系统的理解产生重要影响。

Felker is supported by the Experimental Physical Chemistry Program to continue his ground-state spectroscopic studies of isolated, neutral molecular clusters, using the technique of mass-selective, ionization-detected stimulated Raman spectroscopy (IDSRS) developed in his laboratory. These studies focus on characterizing the intermolecular vibrational level structures of neutral clusters, with primary goals of obtaining information pertaining to intermolecular potential energy surfaces and collective vibrational modes. Systems for study include (1) hydrogen-bonded dimers, including aromatics with water or ammonia, and water dimers, (2) larger hydrogen-bonded and homogeneous aromatic clusters, and (3) free radicals and their complexes with rare gas atoms and small molecules. The project also includes a computational effort to simulate intermolecular Raman spectra to facilitate assignment of observed bands and the extraction of intermolecular potential parameters from experimental results. The overall goal of this research program is to advance the state of knowledge pertaining to how collections of molecules interact with one another. Outcomes from these studies are expected to impact the development of force fields that are used in computer modeling of condensed phase systems, including biologically important molecules, molecules adsorbed onto surfaces and new materials for technological applications. Discovering detailed properties of water-based clusters, in particular, could have important ramifications for improved understanding of environmental and biochemical systems.