Ionization limits in Cu-like and Ni-like high-Zions fromab initiocalculations and wavelength measurements in Rydberg series

The transitions from 3d¹⁰nf (n=7,8) to 3d¹⁰4d, from 3d¹⁰nd (n=6,7) and 3d¹⁰7s to 3d¹⁰4p, and from 3d¹⁰6p to 3d¹⁰4s are identified in the spectrum of laser-irradiated gold Au⁵⁰⁺. The ionization limit derived is in good agreement with ab initio evaluations by means of the relativistic parametric potential method. The small deviations between experimental and theoretical ionization limits are consistent throughout the copper sequence and accurate predictions are given for unobserved elements. Similar methods are used for deriving ionization limits of nickel-like ions from 3d¹⁰ J=0-3d5/2⁹{nf}7/2$ J=1 known transitions and from ab initio estimates.