The adsorption of hydrocarbons on platinum studied by low-energy electron diffraction intensities. The ordered (2x2) overlayers of acetylene and ethylene on the (111) crystal face of platinum

P. C. Stair, G. A. Somorjai

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Abstract

The intensities of the low-energy electron diffraction beams back-scattered from the ordered (2x2) overlayers of acetylene and ethylene on the platinum (111) crystal face are measured by a photographic technique. The intensities are presented in an appendix in the form of normalized diffraction beam intensity versus incident electron energy ( I-V curves). Acetylene spontaneously forms the ordered (2X2) adsorbate on platinum at 300 K and low exposure under ultrahigh vacuum conditions. The intensity profiles reveal that this structure is metastable; and upon heating to 350-400 K for 1 hr it undergoes a transformation to a stable structure with the same (2x2) unit cell size. The acetylene transformation is thought to involve a strengthening of the carbon-platinum bond accompanied by an expansion of the carbon-carbon bond length. Ethylene adsorbes on the platinum (111) surface and with electron beam exposure forms an ordered (2x2) surface structure that is identical to the stable acetylene structure as shown by the intensity profiles.

Original languageEnglish
Pages (from-to)2036-2044
Number of pages9
JournalJournal of Chemical Physics
Volume66
Issue number5
Publication statusPublished - 1976

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Acetylene
Low energy electron diffraction
Hydrocarbons
Platinum
acetylene
platinum
ethylene
electron diffraction
hydrocarbons
Adsorption
Crystals
adsorption
Carbon
crystals
carbon
energy
Bond length
Ultrahigh vacuum
Adsorbates
Surface structure

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

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abstract = "The intensities of the low-energy electron diffraction beams back-scattered from the ordered (2x2) overlayers of acetylene and ethylene on the platinum (111) crystal face are measured by a photographic technique. The intensities are presented in an appendix in the form of normalized diffraction beam intensity versus incident electron energy ( I-V curves). Acetylene spontaneously forms the ordered (2X2) adsorbate on platinum at 300 K and low exposure under ultrahigh vacuum conditions. The intensity profiles reveal that this structure is metastable; and upon heating to 350-400 K for 1 hr it undergoes a transformation to a stable structure with the same (2x2) unit cell size. The acetylene transformation is thought to involve a strengthening of the carbon-platinum bond accompanied by an expansion of the carbon-carbon bond length. Ethylene adsorbes on the platinum (111) surface and with electron beam exposure forms an ordered (2x2) surface structure that is identical to the stable acetylene structure as shown by the intensity profiles.",
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T1 - The adsorption of hydrocarbons on platinum studied by low-energy electron diffraction intensities. The ordered (2x2) overlayers of acetylene and ethylene on the (111) crystal face of platinum

AU - Stair, P. C.

AU - Somorjai, G. A.

PY - 1976

Y1 - 1976

N2 - The intensities of the low-energy electron diffraction beams back-scattered from the ordered (2x2) overlayers of acetylene and ethylene on the platinum (111) crystal face are measured by a photographic technique. The intensities are presented in an appendix in the form of normalized diffraction beam intensity versus incident electron energy ( I-V curves). Acetylene spontaneously forms the ordered (2X2) adsorbate on platinum at 300 K and low exposure under ultrahigh vacuum conditions. The intensity profiles reveal that this structure is metastable; and upon heating to 350-400 K for 1 hr it undergoes a transformation to a stable structure with the same (2x2) unit cell size. The acetylene transformation is thought to involve a strengthening of the carbon-platinum bond accompanied by an expansion of the carbon-carbon bond length. Ethylene adsorbes on the platinum (111) surface and with electron beam exposure forms an ordered (2x2) surface structure that is identical to the stable acetylene structure as shown by the intensity profiles.

AB - The intensities of the low-energy electron diffraction beams back-scattered from the ordered (2x2) overlayers of acetylene and ethylene on the platinum (111) crystal face are measured by a photographic technique. The intensities are presented in an appendix in the form of normalized diffraction beam intensity versus incident electron energy ( I-V curves). Acetylene spontaneously forms the ordered (2X2) adsorbate on platinum at 300 K and low exposure under ultrahigh vacuum conditions. The intensity profiles reveal that this structure is metastable; and upon heating to 350-400 K for 1 hr it undergoes a transformation to a stable structure with the same (2x2) unit cell size. The acetylene transformation is thought to involve a strengthening of the carbon-platinum bond accompanied by an expansion of the carbon-carbon bond length. Ethylene adsorbes on the platinum (111) surface and with electron beam exposure forms an ordered (2x2) surface structure that is identical to the stable acetylene structure as shown by the intensity profiles.

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