AVS 45th International Symposium
    Applied Surface Science Division Monday Sessions
       Session AS-MoM

Paper AS-MoM3
Contribution of a Fano Resonance and Pt-H EXAFS in the Pt L@sub 23@ XANES of Supported Pt Particles: Application to Materials Characterization

Monday, November 2, 1998, 9:00 am, Room 307

Session: Materials Analysis (including Small Dimensions and Synchrotron)
Presenter: D.E. Ramaker, George Washington University
Authors: D.E. Ramaker, George Washington University
B.L. Mojet, Utrecht University, The Netherlands
J.T. Miller, Amoco
D.C. Koningsberger, Utrecht University, The Netherlands
Correspondent: Click to Email
The electronic and geometric effects induced by hydrogen chemisorption on small platinum particles supported on high surface area @gamma@-Al@sub 2@O@sub 3@ and zeolite LTL, were studied by XANES. A new subtraction procedure was developed to separate the electronic from the geometric effects. The Pt-H anti-bonding state (electronic effect) was isolated and was found to have a Fano-resonance line shape. In addition, a significant Pt-H EXAFS scattering (geometric effect) was found for energy values between 0 and 20 eV. The resonance energy, width, and background phase parameter were obtain by least squares fit of the Fano lineshape function to the isolated experimental lineshape. For the Pt/LTL samples the shape and energy of the Fano resonance was found to strongly depend on the acidity/alkalinity of the support material, implying a direct influence of the support on the electronic properties of the Pt particles. The identification of the resonance and Pt-H EXAFS features on these Pt catalysts demonstrates the potential of this new analysis technique for the study of hydrogen chemisorption, metal-promoter, and metal-support effects in catalysis, electrochemistry, and nanoscale technology.