Experimental radiative parameters of 4 f 5 d levels in Pr IV

Abstract

Natural radiative lifetimes of eight 4f5d levels in triply ionized praseodymium (Pr IV) were measured using the time-resolved laser-induced fluorescence (TR-LIF) technique, with the obtained lifetimes ranging from 2.2(2) to 9.8(5) ns. To the best of our knowledge, these are the first experimental lifetime measurements reported for Pr IV levels. Using the measured lifetimes and theoretical branching fractions, semi-empirical weighted transition probabilities and oscillator strengths were deduced for 26 selected Pr IV transitions. The present results fill a gap in the experimental lifetime data for Pr IV and provide experimentally constrained radiative parameters for improving atomic databases of triply ionized lanthanide ions, evaluating theoretical transition data, and supporting plasma diagnostics and astrophysical spectral analyses.