F. Marin et al., HYPERFINE-STRUCTURE OF THE 3-P-3 STATE OF HE-3 AND ISOTOPE SHIFT FOR THE 2-S-3-3-P-3(0)-TRANSITION, Zeitschrift fur Physik. D, Atoms, molecules and clusters, 32(4), 1995, pp. 285-293
The hyperfine structure of the He-3 1s 3p P-3 state and the He-3-He-4
isotope shift is determined by high precision measurements of the 1s 2
s S-3(1) - 1s 3P P-3(J) transition frequencies near 389 nm. A direct f
requency measurement is made without the need for wavelength calibrati
on by tuning a single laser to the atomic frequency, and using a novel
heterodyne method to observe beat frequencies with a stable reference
laser. A fit to a theoretical model of hyperfine structure is used to
determine the hyperfine shifts. Additional off-diagonal mixing effect
s are investigated to resolve a possible systematic discrepancy in the
hyperfine intervals. The final isotope shift without hyperfine struct
ure of 42184308+/-165 kHz is used to deduce an rms nuclear charge radi
us for He-3 of 1.956+/-0.042 fm. This is in good agreement with other
values obtained from atomic isotope shift measurements, and a recent t
heoretical value of 1.958+/-0.006 fm. The present result helps to reso
lve substantial differences in the He-3 nuclear radius derived from el
ectron-nuclear scattering measurements, and it provides a significant
test of the nuclear three-body problem.