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A theoretical study of mutual neutralization of He++H- collisions
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Total and differential cross sections for mutual neutralization in low energy (0.001 eV -100 eV) He + and H − collisions are calculated ab initio and fully quantum mechanically. Atomic final state distributions and isotope effects are investigated. The theoretical model includes dynamics on eleven coupled states of 2 Σ + symmetry where autoionization is incorporated. The potential energy curves, autoionization widths and non-adiabatic couplings of electronic resonant states of HeH are computed by combining structure calculations with electron scattering calculations. The nuclear dynamics is studied using a strict diabatic representation of the resonant states. Effects of rotational couplings between 2 Σ + and 2 Π electronic states are investigated in the pure precession approximation.

National Category
Atom and Molecular Physics and Optics
Research subject
Theoretical Physics
Identifiers
URN: urn:nbn:se:su:diva-128800OAI: oai:DiVA.org:su-128800DiVA: diva2:916696
Available from: 2016-04-04 Created: 2016-04-04 Last updated: 2016-04-11Bibliographically approved
In thesis
1. Theoretical studies of chemical dynamics on excited states, driven by non-adiabatic effects: Charge recombination reactions
Open this publication in new window or tab >>Theoretical studies of chemical dynamics on excited states, driven by non-adiabatic effects: Charge recombination reactions
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis is based on theoretical studies of molecular collisions occurring at relatively low to intermediate collision energies. The collisions are called dissociative recombination (DR) and mutual neutralization (MN). In a molecular quantum mechanical picture, both reactions involve many highly excited molecular electronic states that are interacting by non-adiabatic couplings with each other. The molecular complexes involved in the collisions are relatively (diatomic or triatomic systems) composed of relative light atoms. This allows for accurate quantum chemistry calculations and a quantum mechanical description of the nuclear motions. The reactions studied here are the MN reaction in collisions of H++ H-, Li++ F-, and He++ H- and the DR reaction of H2O+. Rotational couplings are investigated in the study of MN reaction for  He++ H . For some reactions, the electronic resonant states have to be considered. These are not bound states, but are states interacting with the ionization continuum. Electronic structure calculations are combined with electron scattering calculations to accurately compute potential energy curves for the resonant states involved in the DR of H2O+ and the MN of  He++ H. From these calculations, the autoionization widths of the resonant states are also obtained. Once the potential energy curves are computed for the systems, the nuclear dynamics are studied either semi-classically, using the Landau-Zener method or quantum mechanically, employing the time-independent and time-dependant Schrödinger equations. Reaction cross section and final states distribution are computed for all the reactions, showing significantly large cross section at low to intermediate collision energies. For the MN processes, studied here, not only total cross sections are calculated but differential cross sections as well. Where possible, comparisons with previous experimental and theoretical results are performed

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2016. 88 p.
Keyword
Mutual neutralization, Dissociative recombination, electronic structure, non-adiabatic
National Category
Atom and Molecular Physics and Optics
Research subject
Theoretical Physics
Identifiers
urn:nbn:se:su:diva-128723 (URN)978-91-7649-409-7 (ISBN)
Public defence
2016-05-23, sal, FA32, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.

Available from: 2016-04-30 Created: 2016-04-01 Last updated: 2016-04-20Bibliographically approved

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