Frequency measurement of the 2S-12D transitions in hydrogen and deuterium,new determination of the Rydberg constant

We have performed the first pure frequency measurement of the 2S-12D two-ph oton transitions in atomic hydrogen and deuterium, These frequencies are co mpared to two optical standards, the CO2 laser stabilized on the OsO4 molec ule and the optical rubidium laser standard (LD/Rb) (namely, a laser diode at 778 nm stabilized on the 5S(1/2)-5D(5/2) two-photon transition of rubidi um), The main part of the experiment is located in the Laboratoire Kastler- Brossel (LKB), one part of the frequency chain is in the Laboratoire Primai re du Temps ct des Frequences (LPTF), and two 3 km long optical fibers link the two parts of this experiment, The new value of the Rydberg constant is R-infinity = 109 737.315 686 06 (79) cm(-1).