1πσ* or 1nσ* mediated dissociation of X-H and X-CH3 bonds (where X = N, O or S) has been studied herein, progressing previous work into the role of 1πσ* and 1nσ* states as mediators for excited state relaxation. By investigating the role of these states in excited state dynamics of sub-units and analogues of biomolecular systems, spectroscopic signatures can be observed with greater ease. These signatures may then be extended to elucidate the role of these dissociative states in excited state relaxation processes of more realistic systems, namely DNA bases and amino acids. The work undertaken in this thesis specifically focuses on 1πσ* mediated hydrogen elimination from imidazole and mequinol, as well as 1πσ* or 1nσ* mediated CH3 elimination in anisole, thioanisole and mequinol. Through the use of time resolved velocity map imaging, the timescale for these dissociation processes can be determined by independently measuring the radicals produced with a characteristic kinetic energy. From these timescales, information about the rate of coupling to these 1πσ* and 1nσ* states can be inferred. The results obtained show that population of these states can occur via several different mechanisms including: direct excitation; coupling through conical intersections; and tunnelling. The results also project the importance of 1πσ* or 1nσ* mediated processes in much larger biological systems, strongly suggesting the need to extend these measurements and begin to bridge the gap between the microscopic, such as DNA bases and amino acids, and the macroscopic, such as oligonucleotides and polypeptides.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:582444 |
| Date | January 2013 |
| Creators | Hadden, David J. |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/57710/ |
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