A theory of double-charge-transfer processes in ion-atom collisions has been developed. The collision energies of interest, in the range 3-10 keV permit the use of semi-classical impact parameter formalism within which Landau-Zener theory has been adapted to describe the coupling that arises indirectly from 2 virtual 1-electron transitions, necessary because the direct 2-electron coupling amplitudes are insignificant in comparison. A consistent treatment of adiabatic and diabatic potential energy curves and techniques needed to locate crossings of the latter type are given. Application to scattering of OH<SUP>+</SUP> and F<SUP>+</SUP> by inert gas atoms require a systematic treatment of non spherical <I>p</I> atomic orbitals in the theory. Explicit rotations from space-fixed to body-fixed co-ordinates at each point in the scattering trajectory revealed that the theory can predict effects, which in theories involving only <I>s</I> orbitals require a rotational coupling operator, in the absence of such coupling. Cross sections for various double-charge-transfer scattering processes are calculated, employing established model 1-electron transfer scattering amplitudes and reproduced well the experimentally observed "reaction windows" of projectile energy loss within which the cross sections are significant. General kinematic factors, rather than the inclusion of a systematic treatment of the non-spherical <I>p</I> orbitals involved in the reactions studied, are primarily responsible for the form of the reaction window.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:637093 |
| Date | January 1997 |
| Creators | Green, P. S. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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