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Pulse radiolysis investigations of solvated electrons

University of British Columbia

The method of Cerenkov Reabsorption Spectroscopy has been used to measure the initial radiation yield of hydrated electrons. The amount of Cerenkov light that is absorbed by concurrently produced radiation products is measured, and can be related to the initial yield of the absorbing species through Beer's Law. The application of the law is not straightforward because of a complicated spatial dependence of both the light source and the concentration of the absorbing species. The problem was solved by (i) using the integrated form of Beer's Law with a correction factor for the spatial dependence of both the light production and the concentration of absorbers and (ii) applying the differential form of the law directly to analytical expressions for the two functions. An initial yield , independent of pH, of 4.0 ± 0.4 was determined for the hydrated electron. This value is discussed in relation to the various models for the radiolysis of water, and in relation to the concepts of presolvation scavenging and high concentration rate constants. The second part of this thesis deals with an attempt to detect chirality, either inherent or induced, on the part of solvated electrons through (i) their reaction with chiral molecules or (ii) their interaction with polarized light. The rate of reaction of solvated electrons with various chiral molecules was measured using the method of kinetic laser spectrophotometry. Computer analysis of the decay curves gave no evidence for species of different reactivity. Therefore, if chiral solvated electrons exist their rate constants in these instances must differ by less than 5% despite scavengers chosen such that the rate constants had a small activation energy and a relatively large preexponential factor. No shift in the plane of polarization as detected by crossed polarizers or difference in the absorption of right and left circularly polarized light by solvated electrons in a chiral solvent, a racemic solvent and a symmetric solvent doped with chiral molecules was observed.

Text

2010-02-05

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http://hdl.handle.net/2429/19726

Chemistry

University of British Columbia

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