Electron-impact ionization ofBe+

The electron-impact ionization cross section for ${\mathrm{Be}}^{+}$ has been measured from threshold to 1600 eV with an absolute uncertainty of 8%. The cross section has a peak value of 46.5 × ${10}^{-18\mathrm{}}$ ${\mathrm{cm}}^2$ at an energy of ∼ 50 eV, and structure ascribed to the excitation autoionization of the $1s2s2p$ state at 118.5 eV is observed. Calculations using the semiempirical formula of Lotz for direct ionization and the semiempirical effective Gaunt-factor formula for excitation autoionization give summed cross-section values which agree well with the experiment over the entire energy range. Comparisons are also made with other calculations and cross sections in the literature.