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Title: Investigations of the production of excited states in ions
Author: Turner-Smith, A. R.
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 1971
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Excitation by thermal energy charge transfer has been postulated as the pumping mechanism responsible for laser action in certain transitions of the recently announced He-Cd and He-Zn laser systems. In this thesis a study of these reactions and others of the same class is presented. The technique employed in the present work overcomes the difficulty in interpretation of data present in previously published studies of this class of reaction, which arose from the failure to distinguish between charge transfer excitation, electron collisional excitation and Penning excitation. The reactions are studied in a flowing afterglow of a rare gas under conditions such that the plasma electrons have insufficient energy to cause appreciable optical excitation. Discrimination between excitation due to charge transfer and Penning reactions is achieved by selective modulation of the relevant reactant particle concentrations. Measurement of the relative emission intensities of transitions in the daughter metal ion enables the relative charge transfer rate to each level in the ion to be determined. A review is presented of the current state of theories of thermal energy charge transfer reactions. In particular, the prediction that the cross section should be largest for reactions in which the energy defect is positive and of order 1000 cm⁻¹ is found to be in accord with the experimental results. Further experimental conclusions relate to the influence of statistical weight and spin of the final level on the reaction rate. Evidence is presented that in certain cases a third body may enhance the reaction rate.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available