Isotope shift of the 543.3 nm laser transition of neon

The isotope shift of the 543.3-nm laser transition of neon is measured to be 1.00+or-0.05 GHz, with neon-22 having a higher frequency than neon-20. A typical interferometer scan is shown. The isotope shifts for several of the prominent 2s and 3s to 2p and 3p laser transitions are also summarized in tabular form. For all four lines, the neon-22 frequency is higher than the neon-20 frequency. This is contrary to the expectation for the reduced-mass isotope effect and indicates that a specific mass effect is predominant.<>