Semi-empirical calculations of radiative rates for parity-forbidden transitions within the 4f² configuration of Ba-like ions La⁺, Ce²⁺, Pr³⁺ and Nd⁴⁺ and 4f¹² configuration of Dy-like Yb⁴⁺

The experimental free ion 4f¹² energy levels for Yb⁴⁺ have been fitted to the standard f-shell free ion Hamiltonian, which includes the major electrostatic and spin–orbit terms as well as various minor contributions like two-body, spin–spin, spin–other-orbit and electrostatically correlated spin–orbit interactions. Then, the fitted values of free ion parameters and the corresponding eigenstates are used to calculate the oscillator strengths for all absorption transitions and the spontaneous emission rates for all magnetic dipole and electric quadrupole transitions, originating from levels of the 4f² configuration in Ba-like ions La⁺, Ce²⁺, Pr³⁺ and Nd⁴⁺, and the conjugate electron configuration 4f¹² in Dy-like Yb⁴⁺ ions. Our calculated results are also compared with some findings available in the literature. Copyright © 2014 IOP Publishing Ltd.