Hyperfine structure of the metastable deuterium atom

The hyperfine separation Δν(2S;D) of the metastable 2 S122 state of the deuterium atom has been measured by an atomic-beam magnetic-resonance method that has been described previously. We found that Δν(2S;D)=40 924.439±0.020 kc/sec. From this result and the ground-state separation Δν(1S;D) we obtain R(D)Δν(2S;D)Δν(1S;D)=18(1.000 034 2±0.000 000 6). Comparison of this value with the corresponding quantity for hydrogen, R(H)=18(1.000 034 6±0.000 000 3), confirms within experimental error the theoretical prediction that R(D)=R(H). © 1956 The American Physical Society.