Electron-impact ionization data for the nickel isonuclear sequence

Atomic data for the electron impact ionization of ions in the nickel isonuclear sequence are reviewed. Calculations have been performed for all charge states in the distorted-wave approximation. In 8 of the 28 ions of the nickel isonuclear sequence, experiment and theory are compared. In many of the ions, excitation-autoionization contributions to the total cross section are found to be quite important. For intermediate charge state ions a large fraction of the experimental cross section may be attributed to ionization from metastable levels of low-lying excited configurations. Maxwellian collisional rate coefficients are calculated from the cross section data and presented in parametrized form. (orig.)