Nuclear effects in atomic spectra

Abstract

The report is concerned mainly with results of optical investigations of hyperfine structure, particularly of isotope structure. Recent work on the nuclear mass effect in He is described. Analysis of ZnI isotope shifts has shown that nuclear mass effects are appreciable for elements about the middle of the periodic table. Isotope shifts in heavy element spectra (where the mass effect is small or negligible) are discussed in some detail and the theory of the effect of finite distribution of nuclear charge (`volume effect') is outlined. Improved methods of reducing data, including the estimation of isotope shift screening corrections, are referred to, as are various anomalies, including the persistent discrepancy between experiment and calculation, to account for which neutron distribution and nuclear polarization effects have been suggested. A brief description of some magnetic hyperfine structure investigations follows. Small discrepancies in comparisons of nuclear magnetic moments obtained by direct methods, with those from atomic beam magnetic deflection or optical spectroscopic hyperfine structure measurements, have been accounted for in terms of finite distribution of charge and magnetic moment in the nucleus.