THE ELECTRON-IMPACT IONIZATION OF AL2+ IONS

The absolute cross section for the ionization of Al2+ from threshold t o 400 eV has been measured using an electron beam modulation technique . The results are significantly higher than those of Crandall et eel, and are in good agreement with recent convergent close-coupling and ps eudo-state R-matrix calculations by Badnell et al for the direct contr ibution to the cross section below 80 eV. In addition, a fast energy-s canning technique has been employed to make detailed measurements of t he cross section between 65 and 117 eV. Considerable structure due to indirect ionization was revealed and many of the individual features c an be identified with particular autoionization processes involving th e excitation of a 2p electron.