Area
Physical Chemistry
Degrees
B.S., 1987, Indiana University
Ph.D., 1993, University of Texas at Austin
Postdoctoral Research, 1993-1995,
University of Iowa
Research Interests
My research centers on the chemistry that occurs on
surfaces. Any heterogeneous chemical reaction actually
takes place at the interface between two phases. Therefore,
an understanding of the mechanisms of these reactions
requires knowledge of the surface characteristics and
the interactions of the surface with the other phase.
Surface chemistry is important in many fields of technological
importance, including corrosion prevention, heterogeneous
catalysis, thin films and coatings, friction and wear,
and semiconductor device manufacture.
I am specifically interested in the surface
chemistry of solids, especially salts and oxides. Much
of the work in surface chemistry has been done on metal
surfaces. The interactions of molecules with salt or
oxide surfaces will be significantly different than
with a metal because of the localization of opposite
charges on the surface (see box). Thus, one aspect of
the research is the characterization of the adsorption
of molecules on a surface and how the surface properties
affect the adsorption.
However, it is the chemistry that adsorbed
molecules undergo on the surface that I am most interested
in. Thermally driven bond cleavage can be enhanced by
the adsorption of molecules onto a surface, because
the molecular fragments may have a stronger interaction
with the surface than the original molecules. If the
necessary energy to break bonds is supplied thermally,
the surface can provide a new pathway to reaction that
is not available in the pure substance. These surface
species may be intermediates in the formation of another
molecule which is yet more stable. This process is the
basis for catalysis, in which the rate of the reaction
is enhanced by the presence of another substance, the
surface in this case.
A very exciting newer area of research
is the photochemistry of molecules on surfaces. Since
photochemical reaction pathways are often different
than thermal pathways, photoexcitation of molecules
on surfaces provides yet another possibility for accomplishing
a desired reaction. Some changes in the wavelength dependence
of photochemistry have been seen for molecules adsorbed
onto metal surfaces, due to photoexcitation of metal
electrons. While this mechanism is not expected for
electrically insulating surfaces, photochemistry of
molecules on semiconducting transition-metal oxides
promises to be a rich area of study.
Selected Publications:
Surface Photochemistry: 6. CH3Br on Pt(111) Journal
of Physical Chemistry, 1989, 93, 7681.
Potassium Promoted Decomposition of Methyl Bromide on
Ag(111) Journal of Chemical Physics, 1991, 94, 1613.
Kinetic Energy Distributions of Sputtered Neutral Aluminum
Clusters: Al - Al6 Nuclear Instruments and Methods in
Physics Research B, 1993, 82, 329.
New Findings on the Sputtering of Neutral Metal Clusters
Surface Science, 1993, 298, 161.
Molecular Photofragmentation during Non-resonant Multiphoton
Ionization of Sputtered Species Surface and Interface
Analysis, 1993, 20, 1007.
Neutral Copper Cluster Sputtering Yields: Ne+, Ar+ and
Xe+ Bombardment Nuclear Instruments and Methods in Physics
Research B, 1994, 90, 518.
Photoproduct Characterization and Dynamics in the 248
nm Photolysis of CH3I Thin Films on Ag(111) Journal
of Physical Chemistry, 1995, 99, 16416.
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