| AVS 57th International Symposium & Exhibition | |
| Actinides and Rare Earths Topical Conference | Monday Sessions |
| Session AC+SS-MoM |
| Session: | Surface Science of Actinides |
| Presenter: | M. Bagge-Hansen, College of William & Mary |
| Authors: | M. Bagge-Hansen, College of William & Mary R.A. Outlaw, College of William & Mary D.M. Manos, College of William & Mary |
| Correspondent: | Click to Email |
The initial oxidation of clean, polycrystalline α-Th from background CO/CO2 and saturation of the Th surface by O2 has been examined in ultrahigh vacuum (p < 2x10-11 Torr, H2) by angle resolved Auger electron spectroscopy (ARAES) and time of flight secondary ion mass spectrometry (ToF-SIMS). Following dissociative adsorption of background CO/CO2, the accompanying oxygen surface population increased at a rate roughly one third that of the carbon, suggesting significant oxygen incorporation into the bulk. The admission of O2, following heating and sputter cleaning of the Th, showed similar behavior in that some oxygen atoms continued to diffuse into the bulk until formation of stoichiometric ThO2 was observed at ~37 L. The thickness of the oxide complex was determined by both ARAES and ToF-SIMS and found to be ~5 nm. The thermal stability of the ThO2 over the temperature range of 25 – 1000°C was also studied. Rapid decomposition of the oxide by CO desorption and subsequent oxygen dissolution into the bulk was observed to occur within a temperature range of ~550-750°C.