The NO-induced (1x2)->(1x1) structural transition of Pt(110): A quantitative RHEED investigation

Autor(en): vonGlan, RE
Korte, U
Stichwörter: 1X2; adatoms; ADSORPTION; adsorption kinetics; auger electron spectroscopy; carbon monoxide; Chemistry; Chemistry, Physical; CO; DESORPTION; electron-solid interactions, scattering, diffraction; LEED; low index single crystal surfaces; NITRIC-OXIDE; nitrogen oxides; PHASE-TRANSITIONS; Physics; Physics, Condensed Matter; platinum; RECONSTRUCTION; reflection high-energy electron diffraction (RHEED); SPECTROSCOPY; SURFACE; surface defects; surface diffusion; surface relaxation and reconstruction; surface structure, morphology, roughness, and topography; thermal desorption spectroscopy
Erscheinungsdatum: 1997
Volumen: 375
Ausgabe: 2-3
Startseite: 353
Seitenende: 366
The adsorption of NO on Pt(110) and its induced (1 x 2)-->(t x 1) structural transition was studied with quantitative reflection high-energy electron diffraction (RHEED). Time/exposure series of rocking curve sets were recorded during on-going adsorption processes. A direct evaluation focusing on the development of reflection intensities and rocking curve shapes in dependence on the NO exposure allowed dosages to be found for the most rapid structural change and for saturation. 10 sets of rocking curves from room temperature adsorption were quantitatively evaluated using an automated fitting procedure in conjunction with dynamic RHEED theory to determine the values of a comprehensive set of structural parameters for the substrate and the adsorbate. We found considerable changes of the Pt relaxations just prior to the transition from the (1 x 2) missing-row reconstruction into the (disordered) (1 x 1) structure. As long as the substrate is (1 x 2) reconstructed, NO adsorbs on bridge sites on the first Pt layer and on hollow sites on the (111) microfacets while in the case of the (1 x 1) structure first-layer top sites are occupied too. As soon as the transition begins, the rearrangement of the first Pt layer provides for additional vacant bridge and top sites in the second layer. These are then occupied while the hollow sites loose their population. (C) 1997 Elsevier Science B.V.
ISSN: 00396028
DOI: 10.1016/S0039-6028(96)01287-3

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