Coherence effects in laser-RF double resonance

An ''amplitude model'' of the laser-RF double-resonance process has been quantitatively verified, providing a complete explanation of the anomalous line shapes observed in studies of Na2 hyperfine structure. We find excellent agreement with new laser-RF double-resonance measurements in low-J'' rotational levels of the X1Σ/sub g/+(v'' = 0) ground state of Na2 as well as with earlier data for J'' = 28. These results confirm the idea that absorption and stimulated-emission Rabi cycles in the presence of the laser field create coherence between the ground-state hyperfine levels when these levels are optically unresolved. A novel ground-state ''quantum beat'' experiment is proposed