Precision measurement of the isotope shift of the 2 3S13 3P0 transition in helium

none4noA heterodyne spectroscopic scheme, using only one laser tuned to the atomic wavelength, is applied to the measurement of the He-3(F = 1/2-1/2 component)He-4 separation for the 2 S-3(1) - P-3(0) transition at 389 nm. The experimental result is 45 394 425(137) kHz and the isotope shift deduced in the absence of hyperfine structure is 42 184 180(139) kHz. A new value of the He-3 nuclear charge radius is obtained, [r2]1/2 = 1.923(36) fm, in a regime of low energy and momentum transfer.openMarin F.; Minardi F.; Pavone F.S.; Inguscio M.Marin F.; Minardi F.; Pavone F.S.; Inguscio M