Abstract

We induce the 2S–nS and 2S-nD (n = 8, 9, 10) transitions in atomic hydrogen by cw doppler-free two-photon spsctroscopy.¹ The advantage of this experiment is the long lifetimes of tho Rydberg states which give small natural widths for the studied transitions: for example, the 10S natural width is 80 kHz, which can give a relative linewidth of 10^–10. Our experiment can lead to a new measurement of the Rydberg constant, more precise than the preceding ones.^2-4 Those measurements were indeed derived from study or the Balmer-α line whoso relative natural width is 6.5 × 10^–8 and were than limited to a precision of 10^–9.

© 1986 Optical Society of America