Mass Dependence of Uranium Isotope Effects in the U(IV)−U(VI) Exchange Reaction

Abstract

Isotope separation of 233U by anion exchange chromatography based on the U(IV)−U(VI) exchange is studied. After long-distance migration, 233U enrichment is observed at the rear band boundary. To examine the isotope effects of 233U, 234U, and 238U, three-isotope plots of local enrichment factors are constructed for the isotopes contained in sample fractions of the eluted uranium band. The results clearly show an anomalous mass dependence for 233U. We previously reported that the even-mass nuclides 232U, 234U, 236U, and 238U show a regular mass-dependence in their isotope separation behaviors, while 235U does not fall on the same line. The isotope effects of the odd-mass nuclides 233U and 235U deviate from the linear mass dependence observed among the even-mass nuclides. The isotope effects observed in chemical exchange are shown to be closely related to the isotope shifts in the atomic spectra of uranium isotopes.