Long-lived isotopes of plutonium were studied using two complementary techniques, high-resolution resonance ionization spectroscopy (HR-RIS) and collinear laser spectroscopy (CLS). Isotope shifts have been measured on the $5f^{6}7s^2{}^7{F}_0\to 5f^{5}6d^{2}7s(J=1)$ and $5f^{6}7s^2{}^7{F}_1\to 5f^{6}7s7p(J=2)$ atomic transitions using the HR-RIS method and the hyperfine factors have been extracted for the odd mass nuclei  ${}^{239,241}\mathrm{Pu}$. CLS was performed on the $5f^{6}7s{}^8{F}_{1/2}\to J=1/2\left(27523.61{\text{cm}}^{-1}\right)$ ionic transition with the hyperfine $A$ factors measured for ${}^{239}\mathrm{Pu}$. Changes in mean-squared charge radii have been extracted and show a good agreement with previous nonoptical methods, with an uncertainty improvement by approximately one order of magnitude. Plutonium represents the heaviest element studied to date using collinear laser spectroscopy.

• Received 8 December 2016

DOI:https://doi.org/10.1103/PhysRevA.95.032506