Laser spectroscopic measurement of the optical isotope shifts of all the naturally occurring Gd isotopes have been made using a collimated atomic beam system. The isotope shift and hyperfine splitting of all the stable isotopes have been measured for five optical transitions of Gd I at 570.135, 574.466, 574.636, 575.188, and 579.138 nm. The data were combined with the available muonic and electronic x-ray isotope shift data to extract the specific mass shift and the field shift constant. The change in charge radii, λ≊δ〈${\mathit{r}}^2$〉, have been extracted and compared with droplet model predictions. The accuracy of the isotope shift measurements is 0.1% and the extracted charge radius changes have an uncertainty of about 3%.

• Received 4 December 1989

DOI:https://doi.org/10.1103/PhysRevC.42.1911