Mass Spectrometric Determination of Partial Ionization Cross Sections

A review of the measurement of partial electron impact ionization cross sections for rare gas atoms and molecules is presented, with particular regard to the low electron energy regime (<200 eV). Recently developed experimental techniques are surveyed. Predictions of quantal and classical approximations as well as some empirical formulae are compared with the experimental data. In conclusion a set of recommended atomic ionization cross sections is given for electron energies ranging from threshold up to 14 keV. Finally, the existence and measured appearance potentials for the production of doubly ionized rare gas dimers are discussed.