Key points are not available for this paper at this time.
We have recorded the laser-excited resonance fluorescence of one to three Ba^+ ions and observed Bohr's "quantum jumps" when an ion decayed to the metastable ^2D₅₂ state, suddenly quenching its fluorescence. Most of the jumps mark Raman-Stokes scattering from the ^2S₁₂ and ^2D₃₂ levels.
Sauter et al. (Mon,) studied this question.