Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.639147
Title: Negative ion mass spectrometry
Author: Szulejko, J. E.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1981
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Abstract:
The thesis begins with a short introductory chapter which is followed by a survey of the relevant literature which is critically reviewed. The general characteristics of the instrumentation [the VG MM ZAB-2F] is also discussed. Electron Attachment: The negative ion characteristics of both the molecular and the nitrite anions from nitrobenzene were studied as a function of ion source operating parameters such as: (i) the partial pressure of nitrobenzene, and (ii) the partial pressure of argon. From this, a theory was developed and is based on: (i) the production of low energy secondary electrons by 50 eV electron impact, (ii) the low energy secondary electron attachment to nitrobenzene, and (iii) the collisional stabilization by a third body of the metastable molecular anion. A range of compounds were explored for their electron attachment behaviour. Some comments are presented on the reflectivity of negative ions off a gas-metal interface. Charge Inversion: A high translational energy (say 7000 eV) negative ion collides with gas molecules (e.g. helium and nitrogen) and is charge inverted into positive ions. For most systems, the translational energy loss in forming the intact positive ion corresponds closely to the electron affinity and the appearance energy sum. The bond dissociation energy can be determined in some cases. The peak shapes of the fragmentation process are considered in terms of possible alignment polarization effects in the energy transfer process, which could cause asymmetry. The amount of energy transferred in a collision can be as high as 40 eV. A rationale is given for the origin and the expected ion currents of the major negative ions resulting from a 1:1 mixture of methane and nitrous oxide.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.639147  DOI: Not available
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