Isotope shifts and nuclear charge distributions

Abstract

This report is concerned with the measurement and interpretation of the field-dependent isotope shifts in atomic spectra, i.e. shifts due to variations in the nuclear charge distribution. Mass effects are considered only in order to extract the field-dependent shifts from the measured shifts.After a review of experimental techniques and a summary of the basic theory, the isotope shift results are discussed in terms of the results of other experimental investigations of nuclear charge distributions. There are two striking features of isotope shift results for even-even nuclei, their overall smallness and their irregular variation with neutron number over the range of isotopes of an element. The first of these has not yet been satisfactorily accounted for. The irregularities are associated with neutron shell structure, but they cannot be attributed entirely to deformation effects.Experimental isotope shifts and nuclear deformations are tabulated.Recent work on the odd-even staggering effect is reviewed.