High-resolution laser spectroscopy of long-lived plutonium isotopes

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 5f⁶7s²4pt0ex⁷F₀→5f⁵6d²7s4pt0ex(J=1) and 5f⁶7s²4pt0ex⁷F₁→5f⁶7s7p4pt0ex(J=2) atomic transitions using the HR-RIS method and the hyperfine factors have been extracted for the odd mass nuclei 239,241Pu. CLS was performed on the 5f⁶7s4pt0ex⁸F1/2→J=1/20.28em0ex(270.16em0ex523.614.pt0excm^-1) ionic transition with the hyperfine A factors measured for ²³⁹Pu. 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.