Formation and structure of a (√19 × √19)R23.4°-Ge/Pt(1 1 1) surface alloy

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Title:	Formation and structure of a (√19 × √19)R23.4°-Ge/Pt(1 1 1) surface alloy
Authors:	Ho, C.-S., Banerjee, S., Batzill, M., Beck, D.E., Koel, B.E.
Contributors:	Department of Chemical and Materials Engineering, Tunghai University
Keywords:	Alkali ion scattering;Alloy surfaces;Atomic positions;Co and no;Ge atoms;Local structures;Long-range orders;Low energies;Low energy ion scattering;Low-energy electron diffractions;Pt (1 1 1);Room temperatures;Surface alloys;Surface layers;Temperature-programmed desorptions;X-ray photoelectron diffraction;Xps
Date:	2009
Issue Date:	2013-06-19T09:08:55Z (UTC)
Abstract:	An ordered (√19 × √19)R23.4°-Ge/Pt(1 1 1) surface alloy can be formed by vapor depositing one-monolayer Ge on a Pt(1 1 1) substrate at room temperature and subsequently annealing at 900-1200 K. The long-range order of this structure was observed by low energy electron diffraction (LEED) and confirmed by scanning tunneling microscopy (STM). The local structure and alloying of vapor-deposited Ge on Pt(1 1 1) at 300 K was investigated by using X-ray Photoelectron Diffraction (XPD) and low energy alkali ion scattering spectroscopy (ALISS). XPS indicates that Ge adatoms are incorporated to form an alloy surface layer at ∼900 K. Results from XPD and ALISS establish that Ge atoms are substitutionally incorporated into the Pt surface layer and reside exclusively in the topmost layer, with excess Ge diffusing deep into the bulk of the crystal. The incorporated Ge atoms at the surface are located very close to substitutional Pt atomic positions, without any corrugation or "buckling". Temperature Programmed Desorption (TPD) shows that both CO and NO adsorb more weakly on the Ge/Pt(1 1 1) surface alloy compared to that on the clean Pt(1 1 1) surface. ? 2009 Elsevier B.V. All rights reserved.
Relation:	Surface Science 603 (9) , pp. 1161-1167
Appears in Collections:	[Department of Chemical and Materials Engineering ] Periodical Articles

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