AVS 51st International Symposium
    Surface Science Thursday Sessions
       Session SS1-ThA

Paper SS1-ThA5
Interactions of S-containing Molecules and Water Vapor with Polycrystalline UO@sub 2@

Thursday, November 18, 2004, 3:20 pm, Room 210B

Session: Metal Oxides and Clusters IV: Oxide Surface Chemistry
Presenter: B.V. Yakshinskiy, Rutgers, The State University of New Jersey
Authors: B.V. Yakshinskiy, Rutgers, The State University of New Jersey
T.W. Schlereth, Rutgers, The State University of New Jersey
M.N. Hedhili, Rutgers, The State University of New Jersey
T.E. Madey, Rutgers, The State University of New Jersey
Correspondent: Click to Email
The interaction of sulfur dioxide (SO@sub 2@), thiophene (C@sub 4@H@sub 4@S) and water vapor (D@sub 2@O) with a polycrystalline stoichiometric UO@sub 2@ and oxygen-deficient UO@sub 2@ surfaces has been studied under UHV conditions over the temperature range 100 K to 600 K, using XPS (X-ray photoelectron spectroscopy) and TPD (temperature programmed desorption). This work is motivated by potential catalytic applications of stockpiles of depleted uranium. All three molecules are relatively unreactive on the stoichiometric UO@sub 2@ surface, they adsorb and desorb in molecular form. The creation of oxygen vacancies by 1.5 keV Ar ion sputtering is found to enhance the UO@sub 2@ surface reactivity towards the desulfurization of C@sub 4@H@sub 4@S and SO@sub 2@ and the dissociation of water with formation of OD species. Heating of the oxygen-deficient surface with a preadsorbed water monolayer causes desorption of molecular D@sub 2@. The oxygen remains and restores the sample surface to its initial stoichiometric state. The healing of sub-surface defects occurs through thermal diffusion of atoms from the sample bulk at ~ 500 K.