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

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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.