Abstract
This thesis presents experimental data on the dissociative recombination reaction between electrons and the molecular ions, oxygen, nitric oxide, and nitric-oxide-dimers, as well as a computational study of the reaction. The presented research is performed in the context of aeronomy. The products of the dissociative recombination reaction constitute an important part of planetary airglow and is specifically of importance to the green-line and red-doublet airglow emissions of excited atomic oxygen. The experiments were carried out at the ion storage ring, CRYRING, at the Manne Siegbahn Laboratory in Stockholm. The first goal was to present cross sections, thermal rate coefficients, branching fractions, and quantum yields, relevant for atmospheric modelling and airglow research. The second goal was to gain insight in the behaviour of and the mechanisms behind the reaction. The major focus was the investigation of the vibrational-state dependence of the dissociative recombination of molecular oxygen ions. To this purpose a specific ion source was developed and characterised using Cesium-Oxygen charge-transfer reactions. Further subjects of interest for the diatomic atmospheric ions were the electron-energy dependence, possible anisotropic behaviour between the incoming electron and the molecular axis, the statistical behaviour of the branching in the dissociative recombination reaction in contrast to the quantum-chemical behaviour, and the radiative lifetime determination of a metastable state. The study of the nitric-oxide dimer ion focussed on the super dissociative recombination, i.e., the highly efficient cross section observed in dimer ions, the frequently observed three-body break up in polyatomic ions, the possible localisation of the electron capture, and the dissociation dynamics involved. The presented computational study involves a new approach to the dissociative recombination reaction and focusses on the effect of Rydberg-valence couplings and of autoionisation on the dissociative recombination cross section
