Abstract:
Doppler-free two-photon absorption was used to observe the 2S–8D and 2S–10D transitions in atomic hydrogen and deuterium with a relative width of ~ 1.8 X 10– 9. A comparison between the wavelengths of these transitions and that of an iodine-cell-stabilized He–Ne laser yielded a new value ofthe Rydberg constant R∞ = 109737.31569 ± 0.00006 cm– 1.