Measurements of cross sections for the ionization of Na+ to Na2+ and K+ to K2+ by electron impact

Cross sections have been measured for the reaction Na + +e -> Na 2+ +2e for electrons with energies between threshold and 3500 ev. Similar cross sections of K + ions have also been measured for electron energies up to 3000 ev. The errors are estimated to be less than ±6% over a wide range of electron energies and the results agree with those of Hooper et al. , which were confined to electron energies up to 1000 ev.