SusChEM: Chemical Dynamics of Polyatomic Molecules at Surfaces: New Insights from State-Selected Studies

Tufts University, Medford MA

Investigators

Abstract

In this award, funded by the Chemical Structure, Dynamics and Mechanisms (CSDM-A) Program of the Division of Chemistry, Professor Arthur Utz of Tufts University and his graduate and undergraduate student colleagues are studying the reactivity of molecules with vibrational excitation on catalytically-active metal surfaces. Scientists believe that metal-atom vibrations on some surfaces may significantly enhance the reactivity of molecules on the surface. Prof. Utz's research uses molecules with vibrational excitation to probe this effect on a variety of metal surfaces. The goal of research like this is to learn more about the way that gas-surface reactivity can be enhanced with catalytic metal surfaces. Studies like this could lead the way to improved catalysts for industrial processes. Students working in the Utz group receive training in ultrahigh vacuum methods as well as in the use of lasers and sophisticated optical systems. Prof. Utz and his group are also involved in educational outreach to underserved schools in Boston. Prof. Arthur Utz and his research group conduct detailed surface-molecule scattering experiments to probe the ways in which surface metal vibrations modulate catalytic reactivity on a variety of transition metal surfaces. Lasers are used to excite vibrations in molecules entrained in a molecular beam incident upon a variety of transition metal surfaces. Differences in reactivity are probed by monitoring the production of different products as a function of surface temperature and corrugation. Specific reactant gases to be studied include: water, ammonia, methanol, carbon dioxide, ethane and methane. Metals to be studied include: Ni, Pt, Cu and Ru. Questions to be asked include: (1) What are the factors (e.g. identity of dissociation fragments and/or metal surface, local surface structure, etc.) that result in significant modulation of reactivity, and how general is this effect? (2) Is the modulation of reactivity greater at under-coordinated atoms that may undergo larger amplitude motion at a given level of vibrational excitation? (3) Can surface temperature dependence of state-resolved reactivity measurements be used to ascertain details of reaction mechanisms (e.g. barrier height determination)? The Utz research group includes active involvement by undergraduates (Tufts University as well as Stonehill College) in authentic research. Educational outreach takes place with teachers at Josiah Quincy Upper School in Boston's Chinatown neighborhood, designing hands-on activities that complement curricular standards.