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Title: LEED analysis of acetylene and ethylene chemisorption on the Pt(111) surface: Evidence for ethylidyne formation

Abstract

The stable surface species formed from the chemisorption of acetylene (C/sub 2/H/sub 2/) or ethylene (C/sub 2/H/sub 4/) on the Pt(111) surface (Tapprox.300--350 K) has been studied by a low-energy electron diffraction intensity analysis. High resolution electron energy loss spectra reported by Ibach et al. have been interpreted by comparison to infrared data on relevant model compounds. The surface species most consistent with these studies is ethylidyne ( C--CH/sub 3/). The species is coordinated to a threefold surface site with the C--C axis normal to the surface within an uncertainty of approx.15/sup 0/. A saturated C--C bond length of 1.50 +- 0.05 A and three equivalent Pt--C bond lengths of 2.00 +- 0.05 A are determined by the LEED analysis and are consistent with the reported structures of ethylidyne in organometallic clusters. The ethylidyne group forms readily upon exposure of C/sub 2/H/sub 4/ to the Pt(111) surface at Tapprox.300 K with the loss of one hydrogen atom per ethylene. The complete conversion of C/sub 2/H/sub 2/ to ethylidyne requires the presence of hydrogen atoms and proceeds rapidly at Tapprox.350 K. By comparison to reported reaction mechanisms on related transition metal clusters it seems likely that vinylidene ( C=CH/sub 2/) ismore » an intermediate in both reactions.« less

Authors:
; ;
Publication Date:
Research Org.:
Materials and Molecular Research Division, Lawrence Berkeley Laboratory, and Department of Chemistry, University of California, Berkeley, California 94720
OSTI Identifier:
6480122
Resource Type:
Journal Article
Journal Name:
J. Chem. Phys.; (United States)
Additional Journal Information:
Journal Volume: 70:5
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ACETYLENE; CHEMISORPTION; ETHYLENE; ELECTRON DIFFRACTION; EXPERIMENTAL DATA; INFRARED SPECTRA; ISOLATED VALUES; MEDIUM TEMPERATURE; PLATINUM; SURFACES; VINYLIDENE RADICALS; ALKENES; ALKYNES; CHEMICAL REACTIONS; COHERENT SCATTERING; DATA; DATA FORMS; DIFFRACTION; ELEMENTS; HYDROCARBONS; INFORMATION; METALS; NUMERICAL DATA; ORGANIC COMPOUNDS; PLATINUM METALS; RADICALS; SCATTERING; SEPARATION PROCESSES; SORPTION; SPECTRA; TRANSITION ELEMENTS; 400200* - Inorganic, Organic, & Physical Chemistry

Citation Formats

Kesmodel, L L, Dubois, L H, and Somorjai, G A. LEED analysis of acetylene and ethylene chemisorption on the Pt(111) surface: Evidence for ethylidyne formation. United States: N. p., 1979. Web. doi:10.1063/1.437772.
Kesmodel, L L, Dubois, L H, & Somorjai, G A. LEED analysis of acetylene and ethylene chemisorption on the Pt(111) surface: Evidence for ethylidyne formation. United States. doi:10.1063/1.437772.
Kesmodel, L L, Dubois, L H, and Somorjai, G A. Thu . "LEED analysis of acetylene and ethylene chemisorption on the Pt(111) surface: Evidence for ethylidyne formation". United States. doi:10.1063/1.437772.
@article{osti_6480122,
title = {LEED analysis of acetylene and ethylene chemisorption on the Pt(111) surface: Evidence for ethylidyne formation},
author = {Kesmodel, L L and Dubois, L H and Somorjai, G A},
abstractNote = {The stable surface species formed from the chemisorption of acetylene (C/sub 2/H/sub 2/) or ethylene (C/sub 2/H/sub 4/) on the Pt(111) surface (Tapprox.300--350 K) has been studied by a low-energy electron diffraction intensity analysis. High resolution electron energy loss spectra reported by Ibach et al. have been interpreted by comparison to infrared data on relevant model compounds. The surface species most consistent with these studies is ethylidyne ( C--CH/sub 3/). The species is coordinated to a threefold surface site with the C--C axis normal to the surface within an uncertainty of approx.15/sup 0/. A saturated C--C bond length of 1.50 +- 0.05 A and three equivalent Pt--C bond lengths of 2.00 +- 0.05 A are determined by the LEED analysis and are consistent with the reported structures of ethylidyne in organometallic clusters. The ethylidyne group forms readily upon exposure of C/sub 2/H/sub 4/ to the Pt(111) surface at Tapprox.300 K with the loss of one hydrogen atom per ethylene. The complete conversion of C/sub 2/H/sub 2/ to ethylidyne requires the presence of hydrogen atoms and proceeds rapidly at Tapprox.350 K. By comparison to reported reaction mechanisms on related transition metal clusters it seems likely that vinylidene ( C=CH/sub 2/) is an intermediate in both reactions.},
doi = {10.1063/1.437772},
journal = {J. Chem. Phys.; (United States)},
number = ,
volume = 70:5,
place = {United States},
year = {1979},
month = {3}
}