We have made new measurements of the 85Rb 5s−ns Doppler-free two-photon transitions (n = 14–50) with estimated accuracy of better than 1 part in 108. The wavelength of our dye laser was measured by using photographic Fabry-Perot interferometry. Our results differ systematically by as much as 7 parts in 108 from the previous measurements of Lee et al. [Opt. Lett. 3, 141–143 (1978)], who proposed that these two-photon transitions be used as reference lines for dye-laser wavelength calibration. The observed discrepancies cannot be explained by known systematic shifts of the Rb levels in the thermionic diode detectors employed in both experiments. We have confirmed the accuracy of our interferometric wavelengths by measuring Doppler-free saturated absorption lines in 127I2. These results suggest that recently reported Rydberg-state measurements in Li, K, Rb, and Cs, which were calibrated with respect to the previous measurements of the 85Rb 5s−ns transitions, may require revision.
© 1985 Optical Society of America
Craig J. Sansonetti and K. H. Weber′, "High-precision measurements of Doppler-free two-photon transitions in Rb: new values for proposed dye-laser reference wavelengths," J. Opt. Soc. Am. B 2, 1385-1391 (1985)