Electron Impact Ionization Cross Sections of the Ga and In Atoms.

Absolute electron impact cross sections for single, double, and triple ionization of gallium and indium have been measured from 0 to 200 eV. Beams of Ga and In atoms are formed by charge transfer neutralization of 3 keV ion beams with triethylamine or xenon. The cross sections differ considerably from the only previous measurement and are significantly larger than the predictions of various empirical formulas and classical and quantum mechanical theories, due in part to significant contributions from autoionization The double ionization cross sections appear to be dominated by ionization of a d electron followed by autoionization, rather that by direct double ionization.