Hyperfine structures of the nd1D(n=3-8) states of 3He I

We have used the beam-foil quantum beat method to measure the hyperfine structure separations F = 3/2 - 5/2 of the 1snd 1D states (n = 3 - 8) of 3He I. We observed the single frequency modulated decay curves of the 1s2p 1P-1snd 1D transitions for times after excitation up to 50 ns, correspondinq to 4 - 5 modulation periods. The frequency obtained (with a precision of 2 - 5%) are compared with other experiments and theory. The frequencies are determined mainly by the singlet-triplet energy separations and mixing factors for the He I D-states. The results agree with the same parameters obtained from other recent level-crossing measurements in strong magnetic field mixing of the singlet-triplet states. (orig.)