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Title: Charge-permutation reactions of gas-phase ions
Author: Kingston, R. G.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1986
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Collisions of high translational energy ions with neutral gas targets (N) may result in an alteration in the number or sign of the charge and the internal energy of the ion undergoing reaction. These gas-phase reactions are referred to as charge-permutation reactions. In this thesis several types of charge-permutation reaction have been studied, to glean information on the energetics of the reaction. In particular, for doubly- and triply-charged ions, by measuring translational energy changes of the ion undergoing reaction and from energy release data when the ion undergoes fragmentation. Fragmentation patterns have provided structural information. Charge-stripping reactions of polycyclic aromatic species, Mn+ + N → M^(n+1)++N+e^- have been used to determine ionization energies. Relationships between, the ionization energies of M^2+ and M^3+ and the appearance energy of M^+ have been investigated, the charge-stripping efficiency of the collision gas, the ionization energy, the ion velocity and ion radius, have been derived. Charge-inversion reactions of NO^- leading to NO^+, O^+ and N^+ have revealed the role of neutral species and methods are demonstrated to separate and categorise the consecutive reaction steps. Some fragment ion peaks, of composite nature, have been deconvoluted to show the contributions of the various reactions. Charge-exchange reactions (electron capture) M^n+ + N → M(n-1)+ + N+have been used to assign the electronic states for a series of polycyclic aromatic compounds, where n = 2 or 3. Internal energy distributions of product ions have been measured utilising known breakdown graphs. Empirical relationships between cross-sections for electron capture and the energy balance for the reaction have been formulated. The only reaction studied which occurs unimolecularly is charge separation. M(p+q)+ → Mp+atop a + Mq+atop b From energy release data, intercharge distances have been calculated for multiply-charged polycyclic aromatic ions and structural information inferred. Charge exchange and charge stripping have been used to detect structural differences between three C_6H_6 isomers.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available