Doppler-free two-photon spectroscopy of neon

摘要: Doppler-free two-photon transition between the $3s$, $J=2$ metastable state and $4{d}^{\ensuremath{'}}(\frac{5}{2})$, $J=3$ excited of neon has been performed with a monomode cw dye laser. We have measured hyperfine constants $^{21}\mathrm{Ne}$ to be $A=\ensuremath{-}235.9\ifmmode\pm\else\textpm\fi{}0.6$ MHz $B=11\ifmmode\pm\else\textpm\fi{}9$ MHz. The isotopic shifts for this are $E(^{22}\mathrm{Ne})\ensuremath{-}E(^{20}\mathrm{Ne})=2780.0\ifmmode\pm\else\textpm\fi{}2.5$ $E(^{21}\mathrm{Ne})\ensuremath{-}E(^{20}\mathrm{Ne})=1452\ifmmode\pm\else\textpm\fi{}6$ From these results, possibility slight departure from mass formula cannot rejected.