Langmuir-Blodgett (LB) organic monomolecular (monolayer) films containing fatty acids and their perfluorinated counterparts separate into phases under certain conditions. These perfluorinated surfactant containing mixed-phase systems have been shown to exhibit many favourable attributes in comparison to non- perfluorinated surfactant monolayers. In this thesis project, two of these films were investigated. One film is a 2:1 ratio mixture of arachidic acid (C19H39COOH AA) to perfluorotetradecanoic acid (C13F27COOH PA), which phase-separates into hexagonal domains ~6 ìm large (2:1 ratio of AA to PA 2AA1PA). The other film is a 2:1 mixture of stearic acid (C17H35COOH - SA) to PA, which phase-separates into linear domains ~300 nm wide (2:1 ratio of SA to PA 2SA1PA).<p>
Through the use of atomic force microscopy (AFM), and various synchrotron photoemission electron microscopy-based (PEEM) techniques, the films were characterized. As properties such as molecular organization, and dispersion of the molecules in the film, affect film function, it is necessary to use a variety of techniques to better understand order and composition in the films.<p>
First, the well-known and previously-studied film, 2AA1PA, was used to better understand contrast mechanisms in the energy filtered x-ray photoemission electron microscope (X-PEEM) at the CLS. Through the use of techniques such as secondary electron emission microscopy (SEEM), ultraviolet photoelectron spectroscopy (UPS), and x-ray linear dichroism microscopy (XLDM), the effects of secondary electrons, valence character, and polarization dependence were studied so as to better understand their contribution to contrast in energy-filtered PEEM-based spectromicroscopy.<p>
Second, the composition and organization of a novel system (2SA1PA), was characterized using traditional near-edge x-ray absorption fine-structure (NEXAFS) spectroscopy. As the size of the domains in the 2SA1PA system are below the spatial resolution limit of PEEM spectromicroscopy, methods involving selective phase dissolution, and spectrum subtraction, were used to acquire phase composition and molecular order information.<p>
The high lateral and vertical spatial resolution of AFM allowed physical imaging and confirmation of sample structure, as well as very accurate domain height determination. X-PEEM supplements this with chemical sensitivity using high spatial resolution spectromicroscopy. Therefore, using AFM and X-PEEM as complimentary techniques, it is possible to physically and chemically characterize phase-separated monolayer films.
| Identifer | oai:union.ndltd.org:USASK/oai:usask.ca:etd-12222009-150646 |
| Date | 06 January 2010 |
| Creators | Christensen, Stephen Lynd |
| Contributors | Burgess, Ian, Paige, Matthew F., Urquhart, Stephen G., Pratt, Brian, Ward, Dale E. |
| Publisher | University of Saskatchewan |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-12222009-150646/ |
| 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. |
Page generated in 0.0027 seconds