Absolute cross sections for electron impact ionization and dissociation of O-2(+)

Cherkani-Hassani, H. Belic, D. S. Jureta, Jozo [UCL] Defrance, Pierre [UCL]

Absolute cross sections for electron impact single ionization, dissociative excitation and dissociative ionization of O-2(+) were measured in the energy range from threshold to about 2.5 keV by means of a crossed beam set-up. The analysis of product velocity distributions has been applied in order to (i) separate the three processes and (ii) determine the kinetic energy release distribution of ionic fragments. Dissociation is seen to dominantly follow the ionization and the excitation processes, the maximum of the cross sections being found to be (2.20 +/- 0.09) x 10(-17) cm(2), (5.3 +/- 1.0) x 10(-17) cm(2) and (22.0 +/- 4.6) x 10(-17) cm(2) for simple ionization, dissociative ionization and dissociative excitation, respectively. The total kinetic energy released to the fragments is seen to extend up to about 20 eV.