Time-resolved nonlinear laser-induced fluorescence technique for a combined lifetime and branching-fraction measurement

Abstract

The single-shot time-resolved laser-induced fluorescence (LIF) technique is well established for measuring radiative lifetimes of atomic states. On top 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. This additional information is solely deduced from the temporal nonlinear behavior of the LIF signal during laser pumping. The alternative procedure is based on the fact that atoms that decay spontaneously into the initial state can be re-excited during the same laser pulse, whereas atoms that decay into third levels cannot. First measurements of this kind have been performed on singly ionized iron. Lifetimes, branching fractions, and resulting transition probabilities are presented and compared with literature data.