AVS 49th International Symposium
    Surface Science Wednesday Sessions
       Session SS-WeP

Paper SS-WeP8
Structural, Electronic and Catalytic Properties of Clean and Overlayer-Covered Ir(210)

Wednesday, November 6, 2002, 11:00 am, Room Exhibit Hall B2

Session: Surface Science Poster Session
Presenter: I. Ermanoski, Rutgers, The State University of New Jersey
Authors: I. Ermanoski, Rutgers, The State University of New Jersey
W. Chen, Rutgers, The State University of New Jersey
M.J. Gladys, Rutgers, The State University of New Jersey
J.S. Quinton, Rutgers, The State University of New Jersey
T.E. Madey, Rutgers, The State University of New Jersey
M.D. Ulrich, North Carolina State University
J.E. Rowe, North Carolina State University
Correspondent: Click to Email
We report results on the structure, morphology, electronic and catalytic properties of the Ir(210) surface - clean as well as covered with gaseous and metallic overlayers. The atomically rough Ir(210) surface is morphologically unstable: When Ir(210) is covered with more than 0.6 ML of oxygen and annealed, pyramidal facets exposing {110} and {311} surfaces develop on the initially planar surface. We have used a variety of methods to characterize this surface, including LEED, STM and high resolution soft X-ray photoelectron spectroscopy (HRSXPS) using synchrotron radiation. To prepare an oxygen-free faceted surface, we use catalytic CO oxidation at ~500 K to react the oxygen off and "freeze" the surface in its pre-prepared faceted state. HRSXPS has been employed to investigate core-level features of all the surfaces mentioned. The Ir 4f7/2 core levels are fitted with Doniach-Sunjic lineshapes. Surface and bulk peak identifications are supported by measurements at different photon energies (different electron escape depths) and variable photoemission angles. All of the surface components (first, second and third layer peaks) are identified with core-level shifts positioned at higher binding energies with respect to the bulk. This result is in contrast to previous reports of binding energy inversion on the Ir(100) surface. Using TPD we find evidence for structural sensitivity in a surface reaction, i.e. differences in the chemical reactivity of on the planar and faceted surfaces. Overlayers of Pd and Pt exhibit structural changes upon annealing, and HRXPS measurements show changes in the core-level properties of the overlayers. Supported by US DOE and ARO.