Observation of Fine-Structure Quantum Beats Following Stepwise Excitation in SodiumDStates

Abstract
We report the observation of fine-structure and Zeeman quantum beats in highly excited sodium D states prepared, for the first time in a quantum-beat experiment, by stepwise excitation using two synchronously pulsed dye lasers. We have used this new technique to measure the previously unknown fine-structure intervals of levels 9D and 10D of sodium, the values being, respectively, 124.5±1.5 and 91.5±1 MHz.