The alignment of the bonds in a molecule or the orientations that individual molecules take with respect to each other in a macromolecular structure is of significant importance to understanding the molecular mechanics and the nature of their interactions with their environment. There are a variety of different techniques available to investigate this matter.1,2 In comparison with other widely used techniques such as crystallography and fibre diffraction, linear dichroism (LD) is simpler to apply, less time-consuming and also gives useful information about the transition polarisations.3–5 In the preliminary stages of this work, we tried to optimise the technique in order to collect data of higher quality than had been previously possible for a wide range of different types of molecules with different characteristics. We invented a new method of orienting polar and slightly-polar molecules by changing the surface of polyethylene (PE) films to have oxygen groups on them,making PEOX. Then we tried to combine the improved orientation and LD spectroscopy techniques with fluorimetry to make fluorescence detected linear dichroism (FDLD) to increase the sensitivity and selectivity of our experiments. As all UV-visible spectroscopy techniques, including LD and FDLD, are limited by the small number of UV-active functional groups (chromophores) in molecules, we then turned to vibrational spectroscopy techniques. In particular, we have worked on a new type of polarised Raman spectroscopy - Raman Linear Difference (RLD) spectroscopy. The first RLD spectra had been published in 2011.6 In this work, we used our new PEOX films and the new Raman spectroscopic technique to study the alignment of molecules in the vibrational realm. After recording high resolution polarised vibrational data for a set of small molecules using a Raman microscopy system, we designed a new polarised Raman spectrometer which was built in the final stages of this project. We evaluated the newly built instrument by repeating polarised Raman experiments we had performed on the microscope system and found that the results were a significant improvement.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:647963 |
| Date | January 2014 |
| Creators | Razmkhah, Kasra |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/67618/ |
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