AVS 50th International Symposium
    Surface Science Monday Sessions
       Session SS2-MoM

Paper SS2-MoM10
Chemisorption Bond Weakening on Finite Size Terraces: CO on the Stepped Ru(109) Surface Compared to Ru(001)

Monday, November 3, 2003, 11:20 am, Room 327

Session: Catalysis I: Adsorption and Reactions of Small Molecules at Surfaces
Presenter: T. Zubkov, University of Pittsburgh
Authors: T. Zubkov, University of Pittsburgh
G.A. Morgan, Jr., University of Pittsburgh
J.T. Yates, Jr., University of Pittsburgh
Correspondent: Click to Email
We have compared the bonding energy, compressional LEED structures, and vibrational frequency of chemisorbed CO on the 10 atom wide (001) oriented terrace sites of Ru(109) with chemisorbed CO on the Ru(001) surface as a function of CO coverage. The measurements indicate that the Ru-CO bond energy is significantly smaller on the 22 Å wide (001) terrace sites than on the Ru(001) surface, except at the zero coverage limit where equal bond energies are observed. This results in lower saturation coverage and in a less dense saturated CO overlayer on the terraced surface with finite-width (001) planes. The results are explained by compressive relaxation of the (001) Ru terrace sites, leading to a decrease of the average d-band energy and to weaker chemical bonding of the CO. The implication of a finite-size substrate effect on chemical bonding to transition metal catalyst crystallites is important since, within the framework of this finding, smaller facets will exhibit weaker chemisorptive bonding than larger facets.@footnote *@ @FootnoteText@@footnote *@Work supported by DOE-BES.