High-resolution spectroscopy of the 1S-2Stransition of atomic hydrogen and deuterium

Abstract

Two-photon spectroscopy of the hydrogen 1S-2S transition in a cold atomic beam has reached a resolution Δν/ν of 1 part in ${10}^{11}$ in hydrogen and 7 parts in ${10}^{12}$ in deuterium. The hydrogen and deuterium 1S-2S transition frequencies have been determined with a precision of 1 part in ${10}^{11}$. This leads to an accurate value for the Rydberg constant, while the 1S Lamb shift and the isotope shift are determined with order of magnitude improvements over previous measurements. We describe in detail the 1S-2S spectrometer, calculate the line shape of the resonance, and compare it to the experimental data.