Reaction Rates of Uranium Ions and Atoms with O2 and N2

Abstract

A drift mobility-tube-mass-spectrometer apparatus has been used to study the ion-molecule reaction, U++O2→UO++O, from thermal (300°K) energy to ∼5 eV ion mean energy. At 300°K, the reaction rate is (8.5, −1, +4) × 10−10 cm3/sec and falls slowly with increasing ion energy to ∼ 7 × 10−10 cm3/sec at 5 eV. The corresponding reaction of U++N2 is endothermic and not detected to occur up to ∼5 eV ion energy. Chemi-ionization of uranium by the association reaction U+O2 → UO2++e is detected. An estimate of the total reaction rate for U+O2, including the oxidation branch to produce UO+O, yields a value ∼ 2 × 10−12 cm3/sec at 300°K. Implications of these studies for ion cloud generation in the ionosphere are discussed.