Absolute Experimental Cross Sections for the Ionization of Singly Charged Barium Ions by Electron Impact

The absolute cross sections for the single ionization of Ba/sup +/ ions by electron impact have been measured as a function of incident electron energy over the electron energy range from below threshold (10.001 eV) to approximately 1000 eV. It is found that the cross section increases from 1.94 x 10/sup -16/ cm/sup 2/ to 3.76 x 10/sup -16/ cm/sup 2/ between 15.5 and 18 eV actual incident electron energy. This rapid rise is interpreted as the onset of autoionization. Some evidence of structure occurring near the peak of the cross section curve such as found in the isoelectronic system of Cs is observed, but the relative magnitude of the apparent structure is of the same order as the 90% random error confidence limits and thus cannot conclusively be regarded as being present. 56 refs., 16 figs., 7 tabs.