2S hyperfine structure of atomic deuterium

Abstract

We have measured the frequency splitting between the $(2S,F=1/2)$ and $(2S,F=3/2)$ hyperfine sublevels in atomic deuterium by an optical differential method based on two-photon Doppler-free spectroscopy on a cold atomic beam. The result $f_{\mathrm{HFS}}^{(D)}(2S)=40924454(7)$ Hz is the most precise value for this interval to date. In comparison to the previous radio-frequency measurement we have improved the accuracy by the factor of three. The specific combination of hyperfine frequency intervals for metastable- and ground states in deuterium atom $D_{21}=8f_{\mathrm{HFS}}^{(D)}(2S)-f_{\mathrm{HFS}}^{(D)}(1S)$ derived from our measurement is in a good agreement with $D_{21}$ calculated from quantum-electrodynamics theory.

7 pages, 7 figures