Ordering of ethylidyne on clean and adsorbate covered Pd(111): Influence of the coadsorption of oxygen

Journal Article · Wed Jul 01 04:00:00 EDT 1992 · Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States)

DOI:https://doi.org/10.1116/1.577941· OSTI ID:7039055

Nascente, P A.P. ^[1]; Van Hove, M A; Somorjai, G A ^[2]

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1. Departmento de Fisica Aplicada, Instituto de Fisica Gleb Wataghin'', Universidade Estadual de Campinas, 13081 Campinas, SP (Brazil)
2. Center for Advanced Materials, Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States) Department of Chemistry, University of California at Berkeley, Berkeley, California 94720 (United States)

The adsorption and ordering of acetylene on clean and on oxygen-covered Pd(111) at low temperature (150--170 K) and at room temperature were studied by low-energy electron diffraction and high-resolution electron energy-loss spectroscopy. At low temperature a poorly ordered overlayer of molecularly chemisorbed C{sub 2}H{sub 2} was formed on both clean and O-covered Pd(111). At room temperature C{sub 2}H{sub 2} converted to ethylidyne (C{sub 2}H{sub 3}), which weakly ordered in a ((3){sup 1/2}{times}(3){sup 1/2}) {ital R}30{degree} structure. However, preadsorption of oxygen was found to induce better ordering of C{sub 2}H{sub 3} on Pd(111) by (a) possibly removing the free hydrogen atoms on the surface and (b) interacting with the hydrocarbon species via the coadsorbate induced ordering mechanism. It is proposed that the Pd(111)-((3){sup 1/2}{times}(3){sup 1/2}) {ital R}30{degree}--O+C{sub 2}H{sub 3} ordered overlayer can arise from a combination of dipole--dipole interaction and charge transfer through the substrate.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 7039055
• Journal Information: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States), Journal Name: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States) Vol. 10:4; ISSN JVTAD; ISSN 0734-2101
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ACETYLENE
ADSORPTION
ALKYNES
COHERENT SCATTERING
DIFFRACTION
ELECTRON DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY LOSSES
HYDROCARBONS
LOSSES
METALS
NONMETALS
ORDER-DISORDER TRANSFORMATIONS
ORGANIC COMPOUNDS
OXYGEN
PALLADIUM
PHASE TRANSFORMATIONS
PLATINUM METALS
SCATTERING
SORPTION
SPECTROSCOPY
SURFACE PROPERTIES
TEMPERATURE RANGE
TEMPERATURE RANGE 0065-0273 K
TRANSITION ELEMENTS