A crossed beam study of the multiple ionization of argon by electron impact

A pulsed crossed beam technique incorporating time-of-flight spectroscopy previously developed in this laboratory has now been applied to studies of the multiple ionization of argon by electron impact. Cross sections sigma n for the production of n=1-5 times ionized argon have been determined for impact energies in the range from near threshold to 5300 eV. The measurements cover a wider energy range and extend to higher charge states n than most previous experiments. The results also provide valuable checks on the results of previous measurements which exhibit unexplained discrepancies. In the case of single ionization, the authors' values of sigma 1 are compared with available threshold predictions.