Merged beam study of the associative ionisation (C+, N+ and O+) + O-

Total cross-sections have been measured for the associative ionisation of C+ + O-, N+ + O- and O+ + O- by means of a merged-beam set-up operating with keV beams. These original measurements might be relevant to the understanding of some astrophysical objects or laboratory-made plasmas (flames and etching plasmas). The magnitude of these cross-sections is particularly large whatever the associating system, as these are in the range of 1 X 10(-14) cm(2) at thermal energies. Their behaviour as a function of energy significantly differs from one system to another, and is characterised by the Wigner law at low energy, and a rapid fall-off at higher energy due to competition with non-associative ionisation processes.