The 4He-3He isotope shift of the 23S1-23P transition is directly measured by Doppler-free absorption spectroscopy with a colour-centre laser operating in single mode around lambda =1.08 mu m. The splitting between the (23S1-23P0) line of 4He and the (23S1, F=3/2-23P0) line of 3He is (811+or-3) MHz, leading to a shift of (33668+or-3) MHz for the transition 23S1-23P between 4He and 3He. This value compares well with previous experimental data but is more accurate. The agreement with the calculated isotope shift is good.
No takes yet. Share an insight, caveat, or question.
Bloch et al. (1985) studied this question.
Synapse has enriched one closely related paper. Consider it for comparative context: