Isotope shifts of electronic $K\alpha$ x-ray transitions have been measured in isotopes of Nd, Sm, Dy, Yb, and Pb using a curved crystal spectrometer. The $\delta 〈r^2〉$ values of the nuclear charge distribution, as derived from the data, are presented. A combination with results from optical isotope shifts yields an improved accuracy for $\delta 〈r^2〉$. The optical mass shifts and the electronic coefficients can also be obtained. A comparison with muonic x-ray isotope shifts is presented for Nd and Pb. Consistancy between electronic and muonic data is noted.

• Received 10 April 1973

DOI:https://doi.org/10.1103/PhysRevC.8.819