The radiation-induced decomposition of glycine is studied using a combination of Near Edge X-ray Absorption Fine Structure (NEXAFS) measurements and density functional theory calculations. Principal Component Analysis was used to determine the number of distinct molecules that were needed to explain the observed changes in the measured spectra, and the emerging absorption features are assigned to various product molecules through comparison with simulated spectra of several model compounds. It is clear from the experiment that the major effect of soft X-ray irradiation is the fragmentation of the molecule, primarily at the carbonyl sites. Peptide formation is shown to occur under irradiation; a condensation reaction initiated by the removal of a carbonyl oxygen is the proposed mechanism. This study utilizes a novel approach to the study of radiation damage that can occur during measurements, and suggests that it may be possible to use simulated model spectra to correct for these effects in measured spectra.<p>
A study of oligothiophene-based molecular semiconductor materials with potential applications in light-emitting and photovoltaic devices is undertaken. Angle-resolved NEXAFS measurements of the star-shaped 4(HPBT) molecules on an amorphous indium surface show a strong dichroic signal indicating a well-ordered, uniformly upright arrangement of planar molecules. The X-ray excited optical luminescence (XEOL) measurements showed several sharp features associated with vibronic splitting of the LUMO-HOMO luminescent transition. The HOMO-LUMO gap determined from the XEOL measurements is 2.28 eV; this value is in agreement with previously published optical measurements as well as with the value that is estimated from the combination of NEXAFS and X-ray emission spectroscopy (XES) measurements. Films formed from blended solutions of 4(HPBT) and the hole-transporting molecular semiconductor PCBM are shown to form a bilayer structure with the PCBM adjacent to the substrate. Annealing causes desorption of the 4(HPBT) from the surface.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:SSU.etd-06232009-123702 |
| Date | 29 June 2009 |
| Creators | Wilks, Regan G. |
| Contributors | Moewes, Alexander, Koustov, Alexandre V. (Sasha), Hirose, Akira, Heske, Clemens, Chang, Gap Soo, Pickering, Ingrid J., Tse, John S. |
| Publisher | University of Saskatchewan |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-06232009-123702/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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