Time-resolved nonlinear laser-induced fluorescence technique for a combined lifetime and branching-fraction measurement - art. no. 012519

The single-shot time-resolved laser-induced fluorescence (LIF) technique is well established for measuring radiative lifetimes of atomic stares. On to p of that, we show that the branching fraction of the pumped transition can be determined and hence also the absolute transition probability, provided that the LIF signal has been sufficiently saturated by the laser pulse. Th is additional information is solely deduced from the temporal nonlinear beh avior of the LIF signal during laser pumping. The alternative procedure is based on the fact that atoms that decay spontaneously into the initial stat e can be re-excited during the same laser pulse, whereas atoms that decay i nto third levels cannot. First measurements of this kind have been performe d on singly ionized iron. Lifetimes, branching fractions, and resulting tra nsition probabilities are presented and compared with literature data.