State-dependent volume isotope shifts of low-lying states of group-IIaand -IIbelements

Results of relativistic multiconfiguration Dirac-Fock calculations with an extended nucleus are used to analyze the volume isotope shifts of the resonance transitions in the group-IIa and -IIb elements as well as in Yb. This is done together with a review of the isotope shift theory, including a critical evaluation and comparison of the semiempirical calculation of volume isotope shifts commonly used today. Electronic factors Fᵢ, proportional to differences of electronic densities over the nuclear volume, are discussed within various approximations and compared with experimental results.