Absolute ionisation cross sections for electrons incident on O + , Ne + , Xe + and Ar i+ (i=1,...,5) ions

Absolute ionisation cross sections for electrons incident on O + , Ne + , Xe + and Ar 1+ ,..., Ar 5+ ions have been measured at electron energies E e between the ionisation threshold E i and 830 eV. The measurements have been performed with crossed electron and ion beams. The comparison of the data for O + and Ne + with results of Aitken and Harrison (see ibid., vol.4, p.1176, 1971) and Dolder et al. (see Rep. Prog. Phys., vol.39, p.693, 1976), respectively, shows agreement within the combined experimental errors. The measured cross sections for ionisation of Ar i+ ions can be reproduced within +or-20% of the empirical formula sigma i,i+1 =1.4*10 -13 ((ln(E e /E i ))/(E e E i ))(eV) 2 cm 2 for the charge states i=1 up to i=5.