This thesis is mainly focused on the new technique of X-ray Birefringence Imaging (XBI). It reports applications of XBI in different research areas and also presents some developments of the fundamental theory of XBI analysis. At the end of the thesis, work on crystal structure determination directly from powder X-ray diffraction data is also included. Chapter 1 and Chapter 2 provide the theoretical background of XBI and introduce the other techniques used in this thesis. As XBI is analogous to Polarizing Optical Microscopy (POM), the introduction begins with a discussion of general optics, which is then expanded to specific case of polarized X-rays. The methodology for structure determination directly from powder X-ray diffraction data is also described. Chapter 3 demonstrates the application of XBI to study liquid crystalline materials, representing the first investigation of liquid-state samples by XBI. The experimental results show that the XBI technique is successful to elucidate the molecular orientational ordering in different liquid crystalline phases, demonstrating that characterization of molecular orientations by XBI is not limited to the solid-state. Chapter 4 explores a novel type of material – bending crystals. As an effective technique to investigate molecular orientations, XBI is shown to provide clear information on the crystal curvature. Both plastic and elastic types of bending crystal are analysed in both static and dynamic experiments. A theoretical analysis of XBI behaviour of a material containing multiple molecular orientations is also established. In Chapter 5, XBI is used to study composite organic materials. The experimental results vindicate the ability of XBI to characterize spatial distribution of molecules in composite samples. Chapter 6 reports XBI behaviour for the novel case in which two different crystals with independent orientations are present in the X-ray beam. The development of an experimental set-up for recording XBI data using a transmission-based polarization analyzer is also reported for the first time. Chapter 7 is focused on structure determination directly from powder X-ray diffraction. Three crystal structures are determined – two different urea co-crystals and one poly-aromatic compound. Chapter 8 summarises the work in this thesis, gives an appraisal of the strengths and limitations of the XBI technique, and proposes some potential research directions for the future.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:753575 |
| Date | January 2018 |
| Creators | Zhou, Yating |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/113810/ |
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