The effect of nuclear polarizability on the isomer shift in electronic atoms

We study the influence of the nuclear polarizability on isomer shifts. For the quadrupole contribution, we can compare our numerical results to previous investigations of Reiner and Wilets. The agreement is quite good. The polarization contribution to the isomer shift is directly proportional to the non-energy weighted sum of B(Elambda)-values from the ground and isomer states respectively. Although the absolute effects are quite large, there tends to be a cancellation effect for the differences between the two states. This is illustrated, albeit rather crudely, by two different model calculations. Since the polarization effect is, like the volume effect, directly proportional to the electron density at the nucleus, the extraction of Δvertical strokepsi(0)vertical stroke2-values from isomer shift measurements remains unaffected. The nuclear parameter, however, contains in general a polarization contribution. (orig.)