AVS 46th International Symposium
    Surface Science Division Monday Sessions
       Session SS1+EM-MoM

Paper SS1+EM-MoM7
The Structure of the CeO@sub 2@(001) Surface and its Reactions with D@sub 2@O

Monday, October 25, 1999, 10:20 am, Room 606

Session: Chemistry on Oxides
Presenter: C.H.F. Peden, Pacific Northwest National Laboratory
Authors: G.S. Herman, Pacific Northwest National Laboratory
Y.-J. Kim, Taejon National University of Technology, Korea
S.A. Chambers, Pacific Northwest National Laboratory
C.H.F. Peden, Pacific Northwest National Laboratory
Correspondent: Click to Email
Angle-resolved mass-spectroscopy of recoiled ions (AR-MSRI) has been used to determine the surface structure of CeO@sub 2@(001). The results indicate that the surface is terminated with 0.5 monolayers of oxygen which gives rise to a zero dipole moment and, thus, a stable surface. The interaction of D@sub 2@O with the CeO@sub 2@(001) surface was studied with temperature programmed desorption (TPD) and x-ray photoelectron spectroscopy (XPS). It was found with TPD that D@sub 2@O desorption occurs in three states with temperatures of 152, 200, and 275 K which are defined as multilayer D@sub 2@O, weakly bound surface D@sub 2@O, and hydroxyl recombination, respectively. O 1s XPS measurements for high D@sub 2@O exposures, where multilayer water desorption was observed in the TPD, resulted in emission from only the substrate and surface hydroxyls. This is likely due to a non-wetting behavior of D@sub 2@O on this surface with the formation of nanosized clusters. An analysis of the O1s XPS data indicates that the surface has a hydroxyl coverage of 0.9 monolayers for large water exposures at 85 K. This is consistent with a model in which the polar CeO@sub 2@(001) surface can be stabilized by a reduction of the dipole in the top layer by the formation of full monolayer of hydroxyls. @FootnoteText@ Pacific Northwest National Laboratory is a multiprogram national laboratory operated for the U.S. Department of Energy by Battelle Memorial Institute under contract number DE-AC06-76RLO 1830.