Structure and Reactivity of Gas Phase Transition Metal Species

在化学系物理化学计划的这个项目中，威斯康星大学麦迪逊分校的James Weisshaar教授将对金属-碳氢分子的反应性和电子结构随温度、压力和中性反应物分子的电子态的函数进行广泛的基础测量。具体地说，将在三个方面进行研究：1)涉及中性过渡金属原子的化学动力学的概述，2)通过时间分辨的双分子碰撞研究小分子在特定尺寸的过渡金属原子团簇上的吸收和脱附，3)应用质量分析阈值电离新技术，获得金属原子小聚集体和金属原子与有机分子形成的团簇的质量比光谱。饱和碳氢分子，例如甲烷和乙烷，是碳的丰富来源，但它们相当惰性。然而，在低能条件下，它们的化学反应活性可以通过过渡金属原子(如镍、铂、铑等)的催化剂显著增强。这一活化过程的物理化学还不是很清楚，这项研究致力于提高我们对金属原子与碳氢分子之间相互作用的了解。这将通过在气相中的受控条件下进行实验来完成，在气相中，不存在可能的溶剂的扰动效应。这项研究具有跨学科的性质，其结果将影响我们对溶液相有机金属化学、多相催化和表面化学的理解。此外，在这些研究中获得的数据将用于开发计算金属原子与碳氢分子之间相互作用势的理论模型和技术。

In this project of the Physical Chemistry Program of the Chemistry Division, Prof. James Weisshaar of the University of Wisconsin at Madison will conduct a broad program of fundamental measurements on the reactivities and electronic structures of metal-hydrocarbon molecules as function of temperature, pressure, and the electronic state of the neutral reactant molecule. Specifically, research will be pursued in three areas: 1) a survey of the chemical kinetics involving neutral transition metal atoms, 2) a study of the absorption and desorption of small molecules on, or from, size specific clusters of transition metal atoms by means of time-resolved bimolecular collisions, and 3) application of the new technique of mass-analyzed threshold ionization to obtain mass-specific spectra for small aggregates of metal atoms and clusters formed by metal atoms and organic molecules. %%% Saturated hydrocarbon molecules, such as, for example, methane and ethane, are abundant sources of carbon, but they are rather inert. Their chemical reactivities can, however, be significantly enhanced under low energy conditions by catalysts of transition-metal atoms such as nickel, platinum, rhodium, and others. The physical chemistry of this activation process is not well understood and this research is devoted to improve our knowledge of the interactions between metal atoms and hydrocarbon molecules. This will be done by conducting the experiments under controlled conditions in the gas phase, in which the perturbing effects of possible solvents are absent. This research is of an interdisciplinary nature and its results will affect our understanding of solution-phase organo-metallic chemistry, heterogeneous catalysis, and surface chemistry. Furthermore, the data obtained in these investigations will be of use in the development of theoretical models and techniques for the calculation of interaction potentials between metal atoms and hydrocarbon molecules.