Isotope Shift in Neon

The theory of isotopic displacement due to the motion of the nucleus has been extended to atoms with any number of electrons (assuming Russell-Saunders coupling) and applied to the transitions $2p^{5}3s-2p^{5}3p$ in neon. Approximate Hartree wave functions have been obtained and orthogonalized. The theory gives a shift in singlet states of 0.0195 ${\mathrm{cm}}^{-1\mathrm{}}$ more than that in triplet states, as against approximately 0.017 ${\mathrm{cm}}^{-1\mathrm{}}$ measured by Nagaoka and Mishima. However, the calculated shift for the singlet transitions is 0.0038 ${\mathrm{cm}}^{-1\mathrm{}}$, as against the experimental value of 0.0332 ${\mathrm{cm}}^{-1\mathrm{}}$. This discrepancy may disappear if better wave functions are found.