Effects of nuclear polarizability on isotope shifts in electronic atoms

The isotope shift in electronic atoms is calculated in second order perturbation theory. We consider multipole ordersλ=0, 1 and 2 forZ=20–82 nuclei. To a good approximation it is directly proportional to the electron density at the nucleus. We study whether the polarization effect modifies the extraction ofδ〈r ²〉 values from isotope shifts measurements and find it to be small but not always negligible. Relative to the volume effect, the polarizability is of the same order of magnitude for electronic as well as muonic atoms.