Electron-Impact Total Ionization Cross Sections of Molecular Ions

The Binary-Encounter-Bethe (BEB) model for electron-impact total ionization cross sections of neutral molecules has been modified for molecular positive ions. The total ionization cross sections for [Formula: see text], [Formula: see text], CD(+), and CO(+) from the modified BEB formula are compared to available experimental data. The theory is in good agreement with experimental data on [Formula: see text], [Formula: see text], and CD(+), but the experimental data by Belic et al. on [Formula: see text], and CO(+) are lower than the theory. The large difference between the theory and experiment on CO(+) is a strong indication of the dominance of the dissociative ionization channel, CO(+)→C(+)+O(+), which was not included in the experiment.