AVS 51st International Symposium
    Surface Science Tuesday Sessions
       Session SS-TuP

Paper SS-TuP24
Characterization of the Near-surface Structure, Composition and Surface Chemistry of Ultrathin Au Films on Pd{111}

Tuesday, November 16, 2004, 4:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: T.G. Owens, University of St. Andrews, UK
Authors: T.G. Owens, University of St. Andrews, UK
C.J. Baddeley, University of St. Andrews, UK
T.E. Jones, University of St. Andrews, UK
T.C.Q. Noakes, CCLRC Daresbury Laboratory, UK
P. Bailey, CCLRC Daresbury Laboratory, UK
Correspondent: Click to Email
There are many examples where bimetallic catalysts are known to outperform their monometallic counterparts. The synthesis of vinyl acetate monomer (VAM) from acetic acid and ethylene by Pd/Au catalysts is one such example exploited commercially by BP. In order to gain a fundamental understanding of the catalytic role of Au, we are interested in how the chemistry of Pd/Au bimetallic surfaces is influenced by surface structure and composition. Previous studies of the Pd{111}/Au system have reported that the first Au monolayer grows psuedomorphically on Pd{111} at 300 K while subsequent growth consists of films possessing a more Au-like structure, i.e. classic Stranski Krastanov growth. Medium Energy Ion Scattering (MEIS) has a unique ability to probe structure and composition of crystalline surfaces as a function of depth with monolayer resolution. In parallel with Scanning Tunnelling Microscopy (STM) measurements, we reveal that Au growth is more complex than previously assumed and identify an interfacial alloy structure with a quite different structure to either Au or Pd. In addition, we report the behaviour of ultrathin Au films as a function of pre-annealing treatment and we probe how the structure and composition of the near surface region is influenced by the adsorption of simple probe molecules.