In recent experimental efforts, the ultracold Na+K team performed photoassociation of their ultracold samples to the excited state manifold converging to the Na(3s) + K(4p) asymptote. Having identified and assigned molecular lines, they set the "up-leg" photoassociation laser to resonance with one of the energy levels, and further added a second "down-leg" beam that couples said level to the rovibronic ground state of the NaK system. Scanning the down-leg frequency to resonance lead to an atom signal revival, as the excited state gets AC-Stark shifted out of up-leg resonance. The revival maximum thereby unveils the ground state position!
