Hydrogen1S−2SIsotope Shift and1SLamb Shift Measured by Laser Spectroscopy

Abstract

We measured the isotope shift of the $1S-2S$ transition in atomic hydrogen and deuterium to be 670.933±0.056 GHz, using Doppler-free two-photon spectroscopy with a frequency-doubled, pulsed, dye laser. The Balmer-$\beta$ line is simultaneously observed in saturated absorption with the fundamental dye-laser output. A comparison of the intervals $1S-2S$ and $2P_{\frac{3}{2}}-4\mathrm{}{D}_{\frac{5}{2}}$ determines the Lamb shift of the $1S$ ground state to be 8.20±0.10 GHz (H) and 8.25±0.11 GHz (D), in agreement with the theoretical values.