Multiple ionization of gallium by electron impact

Abstract

A pulsed crossed-beam technique incorporating time-of-flight spectroscopy has been used to study the ionization of Ga by electrons at energies ranging from near threshold to 2100 eV. Relative cross sections for n-fold ionization where n = 1 to 4 have been normalized by reference to previous low-energy measurements of by Shul and co-workers based on a fast crossed-beam technique. Some large discrepancies have been noted between some of these and other previous measurements. Apart from some structure in the near-threshold behaviour of , the observed general lack of detailed structure in the multiple ionization cross sections is believed to be associated with the creation of many close-lying subshell vacancies. The measurements compare favourably with recent theoretical predictions based on semi-empirical scaling relations.