Spectroscopy and Photodissociation Dynamics Imaging of C-C and C-H Bond Activation by Transition Metal and Metal Oxide Cations

化学系的实验物理化学项目支持马萨诸塞大学阿默斯特分校里卡多·梅茨教授和他的学生的研究。梅茨教授将研究C-C和C-H键被过渡金属和金属氧化物阳离子激活的反应的反应物和中间体的光谱和光解动力学。当反应从反应物进行到产物时，它形成几个中间体(例如，入口通道复合体、插入中间体和出口通道复合体)。通过研究这些中间体的结构和成键，梅茨和他的学生将能够描述该反应的详细机制。振动光谱将被用来研究离子的基电子态的成键。为了研究电子激发后离子的光解离动力学、测量动能释放和碎片各向异性，将建立一种新型的光碎片成像仪。这将确定精确的键强度，是对激发态动力学和激发电子态之间耦合的详细探索。将要研究的反应包括通过金属原子和团簇将甲烷转化为更大的碳氢化合物，以及通过金属氧化物将甲烷转化为甲醇和将苯转化为苯酚。在劳伦斯伯克利国家实验室的高级光源进行的中性金属氧化物和金属卡宾的光电离研究将测量电离能和中性键强度。大量的电子结构计算将是对实验的补充。需要改进的催化剂来优化利用有限的能源，而C-H和C-C键活化的基础研究通过扩大我们对金属催化机理的理解来帮助这一努力。该项目还为研究生和博士后研究人员提供实验和计算物理化学方面的广泛培训。

The Experimental Physical Chemistry Program of the Division of Chemistry supports the research of Professor Ricardo Metz and his students at the University of Massachusetts, Amherst. Professor Metz will study the spectroscopy and photodissociation dynamics of the reactants and intermediates of reactions in which C-C and C-H bonds are activated by transition metal and metal oxide cations. As a reaction proceeds from reactants to products, it forms several intermediates (e.g., entrance channel complexes, insertion intermediates, and exit channel complexes). By studying the structure and bonding of these intermediates, Metz and his students will be able to characterize the detailed mechanism for the reaction. Vibrational spectroscopy will be used to study bonding in the ground electronic states of the ions. A novel photofragment imaging instrument will be constructed to study ion photodissociation dynamics following electronic excitation, measuring kinetic energy release and fragment anisotropy. This will determine precise bond strengths and is a detailed probe of excited state dynamics and the couplings between excited electronic states. Reactions to be studied include the conversion of methane to larger hydrocarbons by metal atoms and clusters and methane to methanol and benzene to phenol conversion by metal oxides. Photoionization studies of neutral metal oxides and metal carbenes carried out at the Advanced Light Source, Lawrence Berkeley National Laboratory, will measure ionization energies and neutral bond strengths. Extensive electronic structure calculations will complement the experiments.Improved catalysts are needed to make optimal use of limited energy resources, and fundamental studies of C-H and C-C bond activation aid in this effort by expanding our understanding of the mechanisms of metal-based catalysis. The project also provides graduate students and postdoctoral researchers with extensive training in experimental and computational physical chemistry.