Transition rates and wavelengths in the X-ray spectra of nickel-like ions (Ag XX-Pb LV)

The n = 3-4 transitions observed in the X-ray spectra of nickel-like ions (Ag XX-Pb LV) have been investigated theoretically by the multiconfigurational Dirac-Fock approach. The effect of the level crossings on the transitions rates of low excitation depopulation transitions is considered both for forbidden and for allowed transitions. A comparison of the ad initio wavelengths with the available observations for the resonance transitions shows that some experimental data must be refined.