This thesis involves laser flash photolysis studies of the kinetic behaviour of photochemical reactions in heterogeneous media with the emphasis on the effects of magnetic fields on the reactions involving triplet radical pairs. Chapters 3 and 4 present results of the effects of magnetic fields on the behaviour of radical pairs in organized systems. Free radicals are known to be involved in many biological processes and are thought to be a major initiator of some types of cancer. As a result, we have determined how free radical behaviour is modified in the presence of a 60 Hz oscillating magnetic field superimposed over a static magnetic field of comparable magnitude. We showed that the effect of an oscillating magnetic field on radical behaviour is identical to that exerted by a static magnetic field of the same strength provided the frequency is low in comparison with radical pair dynamics. We have used a test system involving radical pairs generated in micellar solutions by photolysis of benzophenone in the presence of 1,4-cyclohexadiene. Our results show that radical pair reactions in micellar solutions exhibit the same behaviour under 60 Hz oscillating fields as under static field conditions at any point in time. Given that (a) radicals play an important role in metabolic processes, and (b) that radical behaviour is strongly influenced by magnetic fields, it was clearly necessary to undertake experiments that better mimic in vivo systems. Laser flash photolysis of probe molecules, such as benzophenone and some of its derivatives, leads to a triplet spin-correlated radical pair due to the hydrogen abstraction of the triplet from Bovine and/or Human Serum Albumin. The analysis of the kinetics of the radical pair, where one of them is derived from the protein, in the presence and in the absence of a magnetic field, shows that the protein-probe radical pair is subject to a magnetic field effect. In Chapter 5, the photophysical properties of microheterogeneous systems have been characterized using the triplet state of an appropriate probe. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/4387 |
| Date | January 1998 |
| Creators | Mohtat, Nadereh. |
| Contributors | Scaiano, J. C., |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Detected Language | English |
| Type | Thesis |
| Format | 197 p. |
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