Seminar speaker – Dr. Ian Harrison, Professor, Department of Chemistry, University of Virginia
Title of the Talk: Reaction Dynamics at Catalytic Metal Surfaces
The reactivity of light alkanes impinging on a Pt(111) single crystal metal surface is examined using effusive molecular beams and surface science techniques. Microcanonical rate theory is shown to be useful in modeling the gas-surface reactivity and energy transfer for both non-equilibrium and thermal equilibrium experiments. Dynamical biases are found to reduce the reactivity of the smallest alkanes, methane and ethane, whereas deviation from statistical reactive behavior was not discerned for larger alkanes. For methane and ethane, only the component of translational energy directed along the direction of the surface normal promotes reactivity, rotational energy is a spectator degree of freedom, and molecular vibrational energy is only 40% as efficacious in promoting reactivity as is normal translational energy. The activation energy for dissociative chemisorption of C1-C9 alkanes is found to diminish with increasing Van der Waals attraction between the alkane and surface. These findings are interesting in the context of optimizing chemical transformations involving natural gas which currently consume ~2% of world power. The talk will conclude with a description of the graduate program in Chemistry at UVa.