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Research Group Opportunities Publications Links _____________    |
Core excitation of gases - modeling polymer and biological systems NATURE of STUDIES: You will carry out systematic
studies of the inner-shell excitation spectra of a variety of small
molecules mainly using the McMaster spectrometer. Where appropriate
complementary measurements of gases and/or solids will be carried
out at synchrotron facilities in Madison, WI or Berkeley, CA. The
overall goal is build improved understanding
of the relationship between inner shell (core) excitation spectra
and chemical structure by a combination of comparison of the
spectra of molecules with similar structural elements, and by comparison
with high level ab initio calculations which you will perform. You
will also assist with the maintenance and further development of the
electron spectrometer and its control and acquisition software.
Target molecules are chosen to explore the relationship of inner-shell
spectra to the electronic and geometric structure. Themes of current
interest incude: a) hydrogen bonding. This is very important
in determining the confromation and stability of polymers and biological
macromolecules. Core excitation is a localized probe of unoccupied
electronic structure at a single atom. If this is affected by weak
H-bonds, the core spectra may reflect the presence or absence of hydrogen
bonding. To date there is no unambiguous evidence for a sensitivity
of core spectra to H-bonding. Comparison of the O1s spectra of carboxyllic
acid monomers and dimers would be a suitable approach.b) peptides.
Each amino acid has a unique core spectra, reflecting the structure
of its side chain group. However the C 1s, N 1s and O 1s spectra of
all proteins are very similar due to averaging. How long can a peptide
be and still be readily identified by NEXAFS ? Small peptides are
increasingly recognized as biochemical signal agents, and targets
for pharmaceuticals. Fine tuning our ability to map peptides with
NEXAFS microscopy through fundamental studies is of great interest.
SKILLS ACQUIRED: Knowledge of core excitation
spectroscopy (NEXAFS, ISEELS); knowledge of aspects of instrumentation
(vacuum, mechanical, electronics, gas handling etc); programming;
quantum computations
YOUR THESIS: would report your results and their
analysis in conjunction with theory. It would also describe any instrumentation
improvements you took part in.
SPECIAL BENEFITS: This project is a continuation
of research carried out over the past 15 years on the ISEELS spectrometer
which has resulted in high quality theses of 4 MSc and PhD students
as well as many undergraduate senior theses. The instrumentation works
very reliably. This project best suits someone who wishes to focus
on the spectroscopy and its application to polymer and biological
systems. It would be an excellent preparation for an academic career,
as well as any position involving advanced instrumentation and mathematical
skills. The polymer model studies are funded in part by Dow Chemical
providing industrial links with potential for future jobs.
© 2004 A.P. Hitchcock / McMaster University
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