Mössbauer Studies of Electrostatic Hyperfine Interactions in ²³⁸U, ²³⁶U, and ²³⁴U

The nuclear gamma resonance (NGR) for ²³⁸U, ²³⁶U, and ²³⁴U in the compound (UO₂) Rb (NO₃)₃ has been established at 4.2°K following the alpha decay of PuO₂ sources. The ratios of the electric quadrupole moments of these isotopes have been determined and the electric field gradient at the uranium site has been calculated from the data. The isomer shift in ²³⁴U has been measured for both PuO₂ and PuA1₄ sources and the change in nuclear radius between the excited and the ground state has been calculated.