Multiple ionization of magnesium by electron impact

A pulsed crossed beam technique incorporating time-of-flight spectroscopy of the collision products, which was developed previously in this laboratory, has been successfully adapted to allow studies of multiple ionization of metallic atoms. Cross sections sigma n for the formation of n=1-4 times ionized magnesium have been determined over the wide energy range 8-5300 eV by normalization to cross sections for single ionization of Mg recently measured by Freund et al using a fast crossed beam technique. Cross sections sigma 2 are found to closely approach the authors' values of sigma 1 at our highest impact energies. Comparison is made with previous experiments based on different methods and, in the case of single ionization, results are compared with theoretical predictions.