AVS 52nd International Symposium
    Surface Science Monday Sessions
       Session SS1-MoA

Paper SS1-MoA9
Hydrogen Interactions with Quasicrystalline Aln-; Pd- & n-; Mn Surfaces

Monday, October 31, 2005, 4:40 pm, Room 202

Session: Catalysis for the Hydrogen Economy
Presenter: C.J. Jenks, Ames Laboratory, Iowa State University
Authors: C.J. Jenks, Ames Laboratory, Iowa State University
T.A. Lograsso, Ames Laboratory, Iowa State University
J. Whaley, Sandia National Laboratories
R. Bastasz, Sandia National Laboratories
Correspondent: Click to Email
The interaction of molecular and atomic deuterium with the fivefold surface of icosahedral (i-) Aln-Pdn-Mn using angular-resolved low-energy ion scattering under ultrahigh vacuum conditions will be discussed. i-Aln-Pdn-Mn is known to form a clean laterally-bulk-terminated surface after sputtering and annealing in excess of 800 K. Despite no two layers within a this material being identical, certain types of planes are favored, namely those that are Al-rich (> 77 atomic percent). The density of Al atoms on the clean surface of fivefold i-Aln-Pdn-Mn is about that of Al(111) and thus we compare our results to studies of molecular and atomic hydrogen on Al(111). We are able to confirm, using ion scattering of 2 keV neon ions and direct recoil measurements, previous thermal desorption studies that indicated that molecular deuterium does not dissociate on this surface. Molecular deuterium, likewise, does not dissociate on Al(111). Atomic hydrogen, however, we find readily adsorbs on both surfaces. On fivefold i-Aln-Pdn-Mn we find that atomic deuterium adsorbs on top of the surface and that it strongly attenuates the signals for Al, Pd and Mn along particular azimuthal directions. Based on this information we will discuss the deuterium adsorption geometry on i-Aln-Pdn-Mn and compare the results to those for Al(111). This work is supported by the Director, Office of Energy Research, Office of Basic Energy Sciences under Contracts no. W-405-Eng-82 and DE-AC04-94AL85000.