BUCKLED LAYER STRUCTURE FOR ATOMIC ADSORPTION ON W(100) - THE (ROOT-2X-ROOT-2)R45-DEGREES NITROGEN STRUCTURE FROM ATLEED

MP BESSENT, P HU, A WANDER, DA KING

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Abstract

Adsorption of 0.5 monolayer of N adatoms on W{100} results in a sharp (root 2 X root 2)R45 degrees LEED pattern. The only previous quantitative LEED study of this system gave a simple overlayer model with a Pendry R-factor of 0.55. An exhaustive search has been made of possible structures, including a novel vacancy reconstruction, displacive reconstructions and underlayer adsorption. From this work a new overlayer structure is derived with an R(p) value of 0.22, displaying a considerable buckling of 0.27 +/- 0.05 Angstrom within the second W layer and consequently involving large changes in the interlayer spacings of the surface. The N adatom is pseudo-five-fold coordinated to the W surface, bonding to a second-layer W atom with a nearest-neighbour bond length of 2.13 Angstrom and with the four next-nearest-neighbour W atoms in the surface plane at 2.27 Angstrom. The structure does not resolve the work function anomaly observed on this surface.

Original languageEnglish
Pages (from-to)272-278
Number of pages7
JournalSurface Science
Volume325
Issue number3
Publication statusPublished - 01 Mar 1995

Keywords

  • CHEMISORPTION
  • LOW ENERGY ELECTRON DIFFRACTION (LEED)
  • SURFACE STRUCTURE, MORPHOLOGY, ROUGHNESS, AND TOPOGRAPHY
  • ENERGY-ELECTRON-DIFFRACTION
  • LEED STRUCTURE-ANALYSIS
  • INDUCED RECONSTRUCTION
  • SURFACE-STRUCTURE
  • ALLOY

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