Reactions of atomic thorium and uranium cations with CF4 studied by guided ion beam tandem mass spectrometry

Abstract

The fundamental chemistry of the actinides continues to be an area of interest because of their use in nuclear fuel cycles. Here, the kinetic energy dependences of the reactions of thorium and uranium cations with CF4 were studied using guided ion beam tandem mass spectrometry. The products observed include AnFx+ (An = Th or U, x = 1–3) and CFy+ (y = 1–3). Although most reactions are exothermic according to literature thermochemistry, all cross sections display strong endothermic features indicating a restriction in the reactivity at low energies. For both actinides, only the AnF+ + CF3 product channel is observed at low energies; however, its formation proceeds very inefficiently. These results indicate that the reactions of Th+ and U+ with CF4 are not thermodynamically driven and suggest that the low-energy reactivity results from precise alignment of the reactants.