Measurement of microwave transition frequencies involving the Rydberg states of sodium atoms

The results are presented of measurements of the frequencies of one-, two-, and three-photon resonances with transitions from strongly excited S and D states of sodium to neighboring P and D states. The measurements were made in the principal quantum number range n = 21–38 for oscillator frequencies 39–156 GHz. The measured transition frequencies are in good agreement with the calculated values.