抄録
Doppler-free two-photon absorption spectroscopy was applied to study highly-excited D states of Rb atoms. Using a cw dye laser as an excitation source, transitions from the ground 5S state to nd 2D states (n=11-32) were observed, the ionization energy of the highest state being only 117cm-1. These D doublets are not inverted. The fine structure splittings of these states do not vary as (neff) -3, nor as n-3. The isotope shift of the 85Rb, 87Rb ground states is found to be 160±12MHz. No pressure broadening was observed for these transitions within the instrumental resolution of 15 MHz.
