Interferometric measurement of the 1S1/2-2S1/2transition frequency in atomic hydrogen

Abstract

The 1${\mathrm{S}}_{1/2}$-2${\mathrm{S}}_{1/2}$ transition frequency in atomic hydrogen has been interferometrically measured by comparison with a reference line in ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}_2^{}{}_{}{}^{}$ by Doppler-free two-photon laser spectroscopy. The measured 1${\mathrm{S}}_{1/2}$-2${\mathrm{S}}_{1/2}$ transition frequency of 2 466 061 397(25) MHz is in good agreement with the theoretical predictions of Erickson modified to take account of recent measurements of the Rydberg constant. This measurement can be used to deduce a value for the ground-state Lamb shift and gives the result of 8182(25) MHz which compares with a value of 8173.248(81) MHz predicted by Erickson.