Theoretical-study of Associative Ionization in H+-h- Collisions At Low-energy (0.001-5ev)

A simple mechanism responsible for H+-H- associative ionisation is proposed which selects the (2p sigma u)2 1 Sigma g+ configuration state as the autoionising state relevant to this process. According to results on mutual neutralisation, the HH1 Sigma g+ and B"B1 Sigma u+ adiabatic states of H2 are assumed to be the way of entering the transition region. Quantal calculations have been performed including all dissociation and ionisation channels. The calculated cross section is found to be in agreement with the previous experimental results of Poulaert et al. (1978)

Dynamics of An Elementary Bond-forming Process - Associative Ionization in H(1s) + H(2s) Collisions

Using a merged-beam apparatus, we have measured the absolute cross section for the associative ionization process H(1s) + H(2s) --> H2+e- between 0.5 and 10 eV. The total cross section rises until a maximum of 2.4 x 10(-17) cm2 at the H2+ dissociation threshold (3.4 eV) and exhibits a minimum around 2 eV. We attribute this feature to interferences between two reaction paths. Calculations combining a quantum-defect treatment of the multichannel ionization with a close-coupling treatment of the atom-atom half collision yield results in good agreement with experiment