AVS 50th International Symposium
    Surface Science Thursday Sessions
       Session SS-ThA

Paper SS-ThA3
The Interaction of Methyl Iodide with Surface Defects on UO@sub 2@(100)

Thursday, November 6, 2003, 2:40 pm, Room 328

Session: Oxide Reactions and Catalysis
Presenter: J. Stultz, Los Alamos National Laboratory
Authors: J. Stultz, Los Alamos National Laboratory
S.A. Joyce, Los Alamos National Laboratory
M.T. Paffett, Los Alamos National Laboratory
Correspondent: Click to Email
Actinide materials undergo thermal and non-thermal reactions with adsorbed molecules resulting in chemical transformations leading to degradation and gas generation. In most handling and processing scenarios actinide materials readily oxidize forming an actinide oxide interface. Evidence suggests that unique chemistry occurs and may possibly be driven by surface defect sites at these oxide interfaces. To characterize these interactions and possibly quantify surface defect sites, the thermal reactivity of CH@sub 3@I with a well annealed and sputter defected UO@sub 2@(100) surfaces was investigated. XPS results indicate CH@sub 3@I undergoes dissociative adsorption on UO@sub 2@(100) at 300K in which I reacts and adsorbs selectively at defect sites leaving little or no residual carbon on the surface. Semi-quantification of surface defects was achieved by analysis of the XPS results for moderately high surface defect densities. Low temperature TPD results indicate mono and multilayer CH@sub 3@I desorption characteristics similar to that seen for other metal oxide systems. Additionally, low intensity features in the TPD data suggest trace levels of oxidation of residual surface carbon to form formic acid. LA-UR-03-2698.