Excitation of the n = 4 level of He+ by electron impact on He

The simultaneous ionization and excitation of helium to the n=4 level of He⁺ by 200-eV electron impact on helium has been studied by time-resolved spectroscopy of the λ=4686-\AA{} (n=4→3) line of He⁺. The study revealed that the excitation process is complex. It appears that only about 70% of the excitation of the λ=4686-\AA{} line can be accounted for by direct simultaneous ionization and excitation of the helium atom to the n=4 level of He⁺ under single electron-atom collision conditions.