Hyperfine structure and isotope shift of the 640.2 and 626.6 nm lines of neon

Abstract
A tunable single mode laser has been used to excite the λ = 640.2 and 626.6 nm lines of 20Ne, 21Ne and 22Ne. Using the velocity selective optical pumping method, we have measured the hyperfine structures and isotopic shifts of these two lines. We obtain the following values for the 21Ne hyperfine structure constants of the 2p 9 level : We have also measured isotope shifts and obtained values in good agreement with the mass-shift formula