College of Science
53 An Analysis of Gas-Phase Sulfide and Oxide Bonding to Uranium by Guided Ion Beam Tandem Mass Spectrometry
Steven Peter Krauel (University of Utah); Peter B. Armentrout (Chemistry, University of Utah); Sara L. Rockow (University of Utah); and Brandon C. Stevenson (University of Utah)
Faculty Mentor: Peter B. Armentrout (Chemistry, University of Utah)
An important aspect of actinide chemistry is the elucidation of the nature of the interaction between the actinides and “hard” (O) versus “soft” (S) chalcogen atoms. Understanding these relationships, especially for uranium, can help to elucidate reactivities and chemical properties that can lead to more efficient and safer nuclear waste management programs. Here, U+, UO+, and US+ were prepared in the gas phase, and their kinetic energy dependent cross sections were measured using guided ion beam tandem mass spectrometry. US+ is formed through a barrierless exothermic process when the atomic metal cation reacts with CS2, with a reaction efficiency of 74 ± 15% compared to the cross section predicted by the Langevin-Gioumousis-Stevenson (LGS) model. Reactions with Xe and CO were also studied, and endothermic reactions were modeled to yield 0 K bond dissociation energies (BDEs) of 7.26 ± 0.29 eV (U+-O), 5.75 ± 0.13 eV (U+-S), 6.75 ± 0.27 eV (SU+-O), and 5.25 ± 0.37 eV (OU+-S). These data are sufficient to characterize simple but important bonding differences between uranium and the two chalcogen atoms studied here.