Figure 6: Presently calculated total ionization cross sections (in the units of ) for electron impact ionization of (designated by solid line) in comparison with the various experimental data sets designated by red-triangle—Perrin et al. [7], —Chatham et al. [8], green-circle—Krishnakumar and Srivastava [9], and blue-square—Basner et al. [10] and theoretical data sets designated by blue-line BEB calculations [13, 28] and pulple-circle—Joshipura et al. [16, 17].