Correlation of isotope shifts with |ψ(0)|^2 for actinide configurations*

We have used both Hartree-Fock functions and the pseudorelativistic HX functions of Cowan to examine the relationship between observed isotope shifts and s-electron densities at the nucleus for Cm, Am, Pu, and U. There are significant changes in relative electron densities when the relativistic correction is included which greatly improve the correlation between observed isotope shifts and electron density. The improvement is especially dramatic for those configurations which fit most poorly with HF values of |ψ(0)|2. The slope [S=ΔIS/Δ(4π|ψ(0)|tot2)] per unit effective mass difference is found to be nearly constant for the actinides considered. This allows prediction of isotope shifts for 252Cf-250Cf which have not been measured. Isotope shifts are also predicted for Cm, Am, Pu, and U configurations which have not yet been identified.