AVS 49th International Symposium
    Surface Science Monday Sessions
       Session SS2-MoM

Paper SS2-MoM1
TPD Studies of the Chemistry of CCl@sub 4@ on Fe@sub 3@O@sub 4@ (2x2)-(111) Surfaces in the Presence of Adsorbed D@sub 2@O

Monday, November 4, 2002, 8:20 am, Room C-112C

Session: Oxide Structure and Surface Chemistry
Presenter: K. Adib, Columbia University
Authors: K. Adib, Columbia University
G. Totir, Columbia University
J.P. Fitts, Columbia University
K.T. Rim, Columbia University
G.W. Flynn, Columbia University
R.M. Osgood, Jr., Columbia University
Correspondent: Click to Email
Due to their abundance in the crust of the Earth and their high reactivity, the oxides of iron serve as ideal model mineralogical surfaces in environmental catalysis studies. The relevance of the environmental studies is enhanced by considering the effect of water on the reactivity of iron oxide surfaces. Natural single crystals of @alpha@-Fe@sub 2@O@sub 3@ were cut and polished in the (0001) orientation. They were processed in ultrahigh vacuum to produce a surface selvedge of Fe@sub 3@O@sub 4@ (111)- 2x2 and exposed at ~100 K to D@sub 2@O and CCl@sub 4@. The TPD studies of adsorbed D@sub 2@O indicate a rich surface chemistry with multiple desorption events extending to as high as ~ 800 K consistent with dissociative adsorption of D@sub 2@O on the Fe@sub 3@O@sub 4@ (111) surface. Previous TPD and XPS results indicate that in the absence of D@sub 2@O, CCl@sub 4@ dissociatively adsorbs on Fe@sub 3@O@sub 4@ (111) producing chemisorbed Cl and CCl@sub 2@ which upon subsequent heating of the surface, abstract lattice iron and oxygen atoms to desorb as FeCl@sub 2@ and OCCl@sub 2@, respectively. In the presence of adsorbed D@sub 2@O, it is observed that the production of FeCl@sub 2@ and OCCl@sub 2@ are substantially suppressed indicating that the D@sub 2@O fragments block the surface reactive sites. The evolution of the reaction products of CCl@sub 4@ with the Fe@sub 3@O@sub 4@ surface as a function of pre-adsorbed D@sub 2@O coverage will be presented.