Ionization limits in Cu-like and Ni-like high-<i>Z</i>ions from<i>ab initio</i>calculations and wavelength measurements in Rydberg series

Abstract

The transitions from 3${d}^{10}$nf (n=7,8) to 3${d}^{10}$4d, from 3${d}^{10}$nd (n=6,7) and 3${d}^{10}$7s to 3${d}^{10}$4p, and from 3${d}^{10}$6p to 3${d}^{10}$4s are identified in the spectrum of laser-irradiated gold ${\mathrm{Au}}^{50+}$. 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 3${d}^{10}$ J=0-3${\mathrm{d}}_{5/2}^{9}$${\mathrm{nf}}_{7/2}$ J=1 known transitions and from ab initio estimates.