This thesis is concerned with an experimental study into the effects of weak static magnetic fields on radical recombination reactions, weak magnetic fields being defined as those which are similar to the average hyperfine coupling of the radical pair. It is the aim of this thesis to examine the effect of these weak magnetic fields on the recombination reactions of neutral radical pairs, as influenced by the microenvironments in which they are created, using the technique of time resolved optical absorption spectroscopy. In the introductory chapters the theoretical concepts underlying the phenomenon of magnetic field effects (MFEs) are presented, and experimental methods applied to study these effects are discussed. A variety of structures used to confine the radical pairs after creation are introduced, and their relevant properties are listed. A discussion of the experimental apparatus used to study the MFEs in neutral radical pairs is presented, alongside the methods used for data analysis. The opening two results chapters are concerned with neutral radical pairs contained in synthetic micelles. A variety of minor alterations to both the radical pair and the micelle structure are introduced, such as addition of hydrogen donor molecules to the micelle, and deuteration of one or both members of the radical pair. An experimental investigation is also presented which tests the theoretical prediction that changing the magnetic field strength from absolute zero magnetic field to a very weak field will lead to a large alteration in radical recombination rate. For the first time at weak magnetic field strengths MFEs are demonstrated in synthetic vesicles, and optimised as a function of concentration and temperature, both above and below the phase transition temperature of the vesicle. Lysophospholipid micelles, formed by phospholipid derivatives are investigated, and form a stepping stone between the synthetic micelles and vesicles investigated in earlier chapters and the biologically relevant vesicles formed by phospholipid molecules. A new probe molecule is introduced, and the MFEs are investigated as a function of chemical concentration and solution temperature. Finally, MFEs are investigated in phospholipid vesicles. Experiments are performed in systems of differing chemical composition, and the effect of solution preparation is evaluated.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:410712 |
| Date | January 2004 |
| Creators | Thomas, Philip G. |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://ora.ox.ac.uk/objects/uuid:8105a575-67c8-4e5a-a27f-f2508c47c1d3 |
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