Determination of branching ratios of spectrally unresolved transitions through polarization detection applied to the 5d6p 3D1o and 3P1o levels of Ba

We have developed a new technique for the determination of branching ratios of spectrally unresolved transitions through polarization detection. As an example, Ba atoms created by laser-ablation from a solid sample are excited by a tunable pulsed dye laser to the 5d6p 3D1o and 3P1o states, after which two polarization components of the fluorescence to the 6s5d 3D1 and 3D2 states are detected simultaneously by a pair of colored filters, optical polarizers, and photomultipliers. From the ratio of the fluorescence of two polarization components the branching ratios have been determined to be 0.51 ± 0.02 and 2.11 ± 0.08, for the 5d6p 3D1o and 3P1o states, respectively, down to the 6s5d 3D1 and 3D2 states, with the influence of hyperfine interaction taken into account. The determined branching ratios agree well with the available atomic data.