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Title: Translational energy loss studies of electron capture reactions
Author: Wilkins, A. C. R.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1995
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Translational energy spectroscopy is an invaluable tool in the study of ion-neutral processes. By measuring the change in energy of the projectile ion information can be obtained about the initial and final states of the projectile and the final states of the target (presuming that the target possesses only thermal energy and is initially in its ground state) for a wide range of collisional processes. One such process is that of electron capture where the multiply-charged ion will capture one or more electrons from the target. The Wigner spin-conservation rule has previously been studied for binary collision processes, however the applicability to electron capture reactions has not been studied extensively. Over eighty reaction channels for the single-electron capture by N2+, O2+, C2+ and Ar4+ have been identified, all of which conform with the rule. Of equal significance the spin non-conserved channels which lie in the same energy range are conspicuously absent. With the O2+ and Ar4+ collision systems a rare quintet state is also identified in the primary ion beam. The spin rule appears less stringent for double-electron capture reactions where many spin forbidden reaction channels have been identified. These are explained as being allowed through two consecutive spin-conserved single electron capture channels. The importance of the design of the collision cell is often overlooked in a spectrometer. Two novel collision cells have been constructed; the first, a thin collision cell, was utilised to assess and reduce the collisional broadening aberration in a translational energy loss spectrum. A second larger cell was designed to attenuate the ion beam to a high degree so that the metastable content of an ion beam can be measured using the ion beam attenuation method. Metastable ions play a substantial part in many collisional phenomena and these measurements are used to quantify the previously obtained electron-capture spectra.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available