Measurements of cross sections for the ionization of Li+ and Ba+ ions by electron impact

Abstract

Cross sections have been measured for the reaction Li⁺ +e -> Li²⁺ +2e for electron energies between threshold and 3 keV. The cross section reaches a maximum value 4.15 × 10^-18 cm² ± 6% at an electron energy of 325 eV. At higher energies the results are similar to those of Rapp and Englander-Golden for helium when the latter measurements are scaled classically. The reaction Ba⁺ +e -> Ba²⁺ +2e has been investigated for electron energies between threshold and 2 keV. At an electron energy of 18 eV the cross section increases abruptly from 1.6 × 10^-16 cm² to 4.25 × 10^-16 cm². This is interpreted as the onset of autoionization (inner-shell excitation).