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.
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