Jason F. Weaver - Chemical Engineering at the University of Florida

UF Chemical Engineering > People > Faculty > Jason F. Weaver

	Jason F. Weaver Ph.D., 1998, Stanford University
	Associate Professor
	Ph : 352-392-0869 weaver@che.ufl.edu 331 Chemical Engineering Building

	Areas
	Oxidation of Transition Metal Surfaces
	Surface Chemistry of Metal Nanoclusters
	Radical-Surface Reactions

Our research focuses on advancing the molecular-level understanding of chemical reactions occurring on solid surfaces. Such reactions are fundamental to heterogeneous catalysis and semiconductor processing, yet remain poorly understood at the molecular level. My students and I investigate surface chemical reactions experimentally using sensitive surface spectroscopic techniques combined with reactive beam scattering in ultrahigh vacuum (UHV). This is a powerful approach for probing the mechanistic details of surface reactions as it enables one to prepare atomically clean surfaces and to induce chemical reactions on these surfaces in a highly controlled manner. The combined use of reactive beam scattering and surface analysis also provides comprehensive information about surface chemical reactions since both the gaseous and surface reaction products are analyzed with high resolution. We also use in situ scanning tunneling microscopy (STM) to obtain real-space images of atoms on solid surfaces. Investigations with STM enable us to examine how different, local arrangements of atoms influence the reactivity of a solid surface, and, conversely, how chemical reactions modify surface structures over nanometer dimensions.

Reactivity of Model Catalysts

Keywords : Catalysis / Reaction Kinetics, Energy, Materials, Nanosciences, Surface Science

We are investigating the oxidation and reactivity of model transition-metal catalysts. The basic goal of this work is to utilize highly reactive atomic oxygen beams to oxidize metallic single crystals and nanoclusters in a UHV chamber so that the surface oxygen phases that exist on metal catalysts under industrially relevant conditions (i.e. atmospheric pressure) can be prepared and characterized in the well-controlled ultrahigh vacuum environment. Using this approach, we are gaining new insights for understanding the growth and reactivity of high-concentration oxygen phases that are important in many applications of catalysis. In addition, a key question that we seek to address is how and why the chemical reactivity of metallic nanoclusters is influenced by the size-dependent geometric and electronic structure of the clusters. This is crucial to the successful molecular design of new catalysts for use in applications ranging from pollution control and energy conversion to the production of fine chemicals.

Radical-Surface Reactions

Keywords : Catalysis / Reaction Kinetics, Energy, Materials, Surface Science

Current work is aimed at elucidating the mechanisms and kinetics of reactions induced by the collisions of gas-phase radicals, particularly oxygen atoms, at solid surfaces. This class of surface chemical reactions is central to technological applications that occur in extreme environments, such as in flames and plasmas, and is very interesting from a scientific viewpoint. The collisions of gas-phase radicals at a solid surface can stimulate a variety of chemical phenomena that occur by so-called non-thermal mechanisms, which means that reactions occur without the reactants thermally equilibrating to the surface. We use beam scattering methods to investigate the surface reactions of gaseous radicals, and we have also been using quantum chemical simulations to complement our experimental efforts. Our interest includes developing an understanding of how reaction conditions and surface properties influence the kinetics of radical-surface reactions so that predictive models of radical-surface chemistry can ultimately be developed.

STM image of sulfur atoms ordered in a two-dimensional array on a Pt(111) surface.

Recent Publications

1.	Devarajan, S.P., Hinojosa Jr., J.A. and Weaver, J.F., “STM Study of High- Coverage Structures of Atomic Oxygen on Pt(111): p(2×1) and Pt Oxide Chain Structures”, Surf. Sci., 602 (2008) 3116.
2.	Kan, H.H. and Weaver, J.F., “A PdO(101) Thin Film Grown on Pd(111) in Ultrahigh Vacuum,” Surf. Sci. Lett., 602 (2008) L53.
3	Hinojosa Jr., J.A., Kan, H.H. and Weaver, J.F., “Molecular Chemisorption of O2 on a PdO(101) Thin Film on Pd(111),” J. Phys. Chem. C, 112 (2008) 8324.
4.	Kan, H.H., Shumbera, R.B. and Weaver, J.F., “Adsorption and Abstraction of Oxygen Atoms on Pd(111): Characterization of the Precursor to PdO Formation,” Surf. Sci., 602 (2008) 1337.
5.	Shumbera, R.B., Kan, H.H. and Weaver, J.F., “Temperature Programmed Reaction of CO Adsorbed on Oxygen-Covered Pt(100): Reactivity of High-Coverage Oxygen Phases,” J. Phys. Chem. C, 112 (2008) 4232.