Ionization energies of Cu- and Ni-like ions with Z ≤ 92

Abstract

A two-stage technique is developed to interpolate and extrapolate the ionization energies of Cu- and Ni-like ions along Z with accuracy to the fifth significant digit. I) The first stage consists of scaling the known ionization energies (IE) along Z, which brings the IE(Z)-function to a quasi-straight line. Function straightening detects points where the function’s smoothness breaks down. They are fitted to the IE(Z) curve in the same way as it is usually done in some experiments. Scaling on successive overlapping segments allows a confident extrapolation to the region Z=92. II) The verification of the obtained results in stage I is performed using the parameter of the relativistic model potential of a Dirac equation. The results of techniques I and II agree well up to Z∼92.