Absolute experimental cross sections for the electron-impact multiple ionization of singly charged rubidium ions

The absolute cross sections for the double, triple, and quadruple ionization of ${\mathrm{Rb}}^{+}$ ions by electron impact have been measured from below their respective thresholds to approximately 3000 eV. This determination has been accomplished using a crossed-beam facility in which monoenergetic beams of ions and electrons are caused to intersect at right angles in a well-defined collision volume. The various charged-particle currents, energies, and beam-current density distributions represent the experimental data from which the desired absolute cross sections have been determined. The results obtained with this technique are compared with available theoretical predictions of the appropriate cross sections.