The Hyperfine Structure of Hydrogen and Deuterium

The atomic-beam magnetic resonance method has been applied to measure the h.f.s. separation of the ground state of H and D by observing frequencies of the r-f field required to induce transitions among certain of the magnetic levels of the h.f.s. multiplets in magnetic fields of the order of 1 gauss. The resonance minima were of the theoretical width for transitions which are field independent in the first order. For deuterium we find ${\nu }_{\mathrm{D}}=327.384\mathrm{}\pm 0.003$ Mc which agrees with our previously reported value within the precision claimed for that quantity. For hydrogen we find ${\nu }_{\mathrm{H}}=1420.410\mathrm{}\pm 0.006$ Mc which is less than the value previously reported by 0.06 percent. The ratio of the measured h.f.s. separations, $\frac{{\nu }_{\mathrm{H}}}{{\nu }_{\mathrm{D}}}$, is 4.33867±0.00004.