Investigation of vinyl phosphonic acid/hydroxylated α-Al2O3(0001) reaction enthalpies

L. G. Hector, S. M. Opalka, G. A. Nitowski, L. Wieserman, D. J. Siegel, H. Yu, James Adams

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


The eleven ion vinyl phosphonic acid (VPA) molecule consists of a phosphorus ion that serves as a cationic anchor for two electron-rich functional groups, viz., a tripodal oxygen-rich base and vinyl hydrocarbon tail. Recent inelastic tunneling experiments have implied that VPA binds in a tridentate coordination though its base leaving the vinyl tail free to react with a resin in adhesive bonding applications. Using first-principles total energy calculations, the reaction enthalpies for bonding of a single VPA molecule to selected threefold sites on hydroxylated α-Al2O3(0001) are investigated. Tridentate, bidentate and unidentate coordinations, both with and without liberated water molecules, are examined to determine if the tridentate coordination is favored over the others and the extent to which the VPA molecule is sensitive to surface site geometry. The electron localization function is used to examine the extent of covalent character between the P-O bonds that anchor the VPA fragment to the oxide surface. Some comments on the entropic contributions of the VPA and H2O molecules to the binding energetics are offered, along with a discussion of the effects of H2O placement on the oxide surface and aluminum alloying agents.

Original languageEnglish (US)
Pages (from-to)1-20
Number of pages20
JournalSurface Science
Issue number1
StatePublished - Nov 10 2001


  • Aluminum oxide
  • Surface chemical reaction
  • Tunneling

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry


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