Endothermic reactions of uranium ions with N2, D2, and CD4

An ion beam apparatus is employed to study the reactions of uranium ions with N2, D2, and CD4 at laboratory energies up to 335 eV. The endothermic reaction of U + with nitrogen leads to the product UN + for which a bond dissociation energy D (UN + ) =4.7±0.2 eV is determined, corresponding to DeltaHf(UN + ) =272±7 kcal/mole. Endothermic reactions of U + with D2 and CD4 lead to formation of UD + with D (UD + ) =2.9±0.1 eV and DeltaHf(UD + ) =254±6 kcal/mole. The dependence of experimental reaction cross sections on relative kinetic energy is discussed in terms of simple models for reaction. The proton affinity of uranium is determined, P.A.(U) =238±5 kcal/mole, and this exceptionally high value is compared to other atomic and molecular base strengths