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Sean
A. Peebles, Ph.D. Associate Professor - Physical Chemistry B.Sc., University
of Exeter (UK), 1992 Courses taught CHM 1310, 1410, 1510 General Chemistry I, II CHM 1315, 1415, 1515 General Chemistry Laboratory I, II CHM 3910 Physical Chemistry I (Thermodynamics) CHM 3915 Physical Chemistry Laboratory CHM 3920 Physical Chemistry II (Quantum Chemistry) CHM 4770 Molecular Spectroscopy CHM 5300 Graduate Molecular Spectroscopy |
My current
research interests focus on the
characterization of weakly bound complexes via Fourier-transform
microwave spectroscopy and theoretical methods. The spectroscopic
studies utilize a Fourier-transform microwave spectrometer. This
technique involves the supersonic expansion of a gas mixture (in argon
or helium/neon) into an evacuated vacuum chamber where the molecules
are subsequently probed by microsecond pulses of microwave
radiation. The adiabatic cooling process cools the molecular
expansion to just a few degrees kelvin and hence allows isolation of
very weakly bound complexes, effectively freezing them out of the gas
mixture and providing no mechanism by which they can fall apart.
Currently, I am interested in the study of weak complexes that have the
potential to form so-called C-H hydrogen bonds. These types of
forces are considerably weaker than the conventional hydrogen bonds
that are observed to form between atoms like N-H..O or O-H..O.
Despite their very weak nature, it is important to study such
interactions and quantify their effects to understand their influence
on important biological processes such as protein folding and
carbohydrate structures. More details of the experimental aspects
of my research may be found on the following page http://ux1.eiu.edu/~cfsap/microwave.htm
The
theoretical studies involve both
semi-empirical and ab initio calculations of the structures and
properties of molecules and complexes, with a particular focus on the
changes in various molecular properties that occur upon complexation
(such as bond lengths, electric field gradients, barriers to rotation
of methyl groups etc.). For these calculations we utilize the
Department of Chemistry Tru64 Unix workstation as well as a dedicated
PC in my lab. The theoretical computations complement the
spectroscopic work and aid in spectral assignment as well as providing
a means to understanding the balance of forces that lead to the
geometries that we observe for the weak complexes studied.
The
long term goals of my
research are to
formulate a better understanding of the balance of forces responsible
for the geometries of molecular clusters, ultimately leading to a
quantitative understanding of the interactions in macroscopic condensed
phases.
 Representative
Publications
(undergraduate coauthors denoted by an asterisk)
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