Defect induced surface chemistry: A comparison of the adsorption and thermal decomposition of C2H4 on Rh{111} and Rh{331}

Robert J. Levis, Lisa A. Delouise, Eric J. White, Nicholas Winograd

Research output: Contribution to journalArticle

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Abstract

The adsorption and thermal decomposition of C2H2 on Rh{111} is compared to the atomically stepped Rh{331} surface over a temperature range of 300 to 800 K. Using X-ray photoelectron spectroscopy (XPS) we find that the C 1s spectra as a function of C2H4 exposure exhibit a shift in binding energy (Eb) from 283.5 eV at 1 L C2H4 exposure on both surfaces to 283.8 eV on Rh{33 and to 284.1 eV on Rh{111} at saturation coverage (4 L). Careful analysis of the C 1s Eb value and full width at half maximum as a function of surface temperature after a 10 L exposure of C2H4 at 300 K reveals that a species consistent with a C2H adsorbate composition is formed between 400 and 450 K on Rh{111}. This species is also observed on Rh{331} although at the lower temperature of 375 K. Computer peak deconvolution of the C 1s spectra between 500 and 700 K suggests that a CHads or Cads surface fragment is formed and increases in concentration at the expense of the C2H species as the surface temperature increases. Above 750 K a graphite overlayer is formed on both surfaces. This overlayer, however, exhibits a low degree of carbon π-character bonding on Rh{331}. The adsorption and decomposition mechanisms suggest that the 300 K C2H4 adsorbate on Rh{331} is ethylidyne and that the stepped surface is more thermally reactive than the flat Rh{111} surface.

Original languageEnglish (US)
Pages (from-to)35-46
Number of pages12
JournalSurface Science
Volume230
Issue number1-3
DOIs
StatePublished - May 1 1990

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Surface chemistry
thermal decomposition
Pyrolysis
chemistry
decomposition
Adsorption
Defects
adsorption
defects
surface temperature
Adsorbates
Temperature
Graphite
Deconvolution
graphite
Full width at half maximum
binding energy
Binding energy
fragments
photoelectron spectroscopy

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

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title = "Defect induced surface chemistry: A comparison of the adsorption and thermal decomposition of C2H4 on Rh{111} and Rh{331}",
abstract = "The adsorption and thermal decomposition of C2H2 on Rh{111} is compared to the atomically stepped Rh{331} surface over a temperature range of 300 to 800 K. Using X-ray photoelectron spectroscopy (XPS) we find that the C 1s spectra as a function of C2H4 exposure exhibit a shift in binding energy (Eb) from 283.5 eV at 1 L C2H4 exposure on both surfaces to 283.8 eV on Rh{33 and to 284.1 eV on Rh{111} at saturation coverage (4 L). Careful analysis of the C 1s Eb value and full width at half maximum as a function of surface temperature after a 10 L exposure of C2H4 at 300 K reveals that a species consistent with a C2H adsorbate composition is formed between 400 and 450 K on Rh{111}. This species is also observed on Rh{331} although at the lower temperature of 375 K. Computer peak deconvolution of the C 1s spectra between 500 and 700 K suggests that a CHads or Cads surface fragment is formed and increases in concentration at the expense of the C2H species as the surface temperature increases. Above 750 K a graphite overlayer is formed on both surfaces. This overlayer, however, exhibits a low degree of carbon π-character bonding on Rh{331}. The adsorption and decomposition mechanisms suggest that the 300 K C2H4 adsorbate on Rh{331} is ethylidyne and that the stepped surface is more thermally reactive than the flat Rh{111} surface.",
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Defect induced surface chemistry : A comparison of the adsorption and thermal decomposition of C2H4 on Rh{111} and Rh{331}. / Levis, Robert J.; Delouise, Lisa A.; White, Eric J.; Winograd, Nicholas.

In: Surface Science, Vol. 230, No. 1-3, 01.05.1990, p. 35-46.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Defect induced surface chemistry

T2 - A comparison of the adsorption and thermal decomposition of C2H4 on Rh{111} and Rh{331}

AU - Levis, Robert J.

AU - Delouise, Lisa A.

AU - White, Eric J.

AU - Winograd, Nicholas

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Y1 - 1990/5/1

N2 - The adsorption and thermal decomposition of C2H2 on Rh{111} is compared to the atomically stepped Rh{331} surface over a temperature range of 300 to 800 K. Using X-ray photoelectron spectroscopy (XPS) we find that the C 1s spectra as a function of C2H4 exposure exhibit a shift in binding energy (Eb) from 283.5 eV at 1 L C2H4 exposure on both surfaces to 283.8 eV on Rh{33 and to 284.1 eV on Rh{111} at saturation coverage (4 L). Careful analysis of the C 1s Eb value and full width at half maximum as a function of surface temperature after a 10 L exposure of C2H4 at 300 K reveals that a species consistent with a C2H adsorbate composition is formed between 400 and 450 K on Rh{111}. This species is also observed on Rh{331} although at the lower temperature of 375 K. Computer peak deconvolution of the C 1s spectra between 500 and 700 K suggests that a CHads or Cads surface fragment is formed and increases in concentration at the expense of the C2H species as the surface temperature increases. Above 750 K a graphite overlayer is formed on both surfaces. This overlayer, however, exhibits a low degree of carbon π-character bonding on Rh{331}. The adsorption and decomposition mechanisms suggest that the 300 K C2H4 adsorbate on Rh{331} is ethylidyne and that the stepped surface is more thermally reactive than the flat Rh{111} surface.

AB - The adsorption and thermal decomposition of C2H2 on Rh{111} is compared to the atomically stepped Rh{331} surface over a temperature range of 300 to 800 K. Using X-ray photoelectron spectroscopy (XPS) we find that the C 1s spectra as a function of C2H4 exposure exhibit a shift in binding energy (Eb) from 283.5 eV at 1 L C2H4 exposure on both surfaces to 283.8 eV on Rh{33 and to 284.1 eV on Rh{111} at saturation coverage (4 L). Careful analysis of the C 1s Eb value and full width at half maximum as a function of surface temperature after a 10 L exposure of C2H4 at 300 K reveals that a species consistent with a C2H adsorbate composition is formed between 400 and 450 K on Rh{111}. This species is also observed on Rh{331} although at the lower temperature of 375 K. Computer peak deconvolution of the C 1s spectra between 500 and 700 K suggests that a CHads or Cads surface fragment is formed and increases in concentration at the expense of the C2H species as the surface temperature increases. Above 750 K a graphite overlayer is formed on both surfaces. This overlayer, however, exhibits a low degree of carbon π-character bonding on Rh{331}. The adsorption and decomposition mechanisms suggest that the 300 K C2H4 adsorbate on Rh{331} is ethylidyne and that the stepped surface is more thermally reactive than the flat Rh{111} surface.

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