Effects of potassium on the reaction pathways of CH2 fragment over Mo2C/Mo(1 0 0)

A. P. Farkas, L. Bugyi, Á Koós, F. Solymosi

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The adsorption and surface reactions of CH2I2 on the K-dosed Mo2C/Mo(1 0 0) have been studied by high resolution electron energy loss spectroscopy, X-ray photoelectron spectroscopy and thermal desorption spectroscopy. Potassium is an effective promoter for the rupture of C-I bond in the adsorbed CH2I2. A partial dissociation of this compound occurred even at 100 K and was completed at 190 K at monolayer K coverage. The dissociation was further promoted by the illumination of coadsorbed layer at 100 K. As revealed by HREELS and XPS measurements the primary products of the dissociation are CH2 and I. Methylene was converted to π-bonded ethylene characterized by Tp = 160 K, and di-σ-ethylene with Tp = 350 K. Other products of the surface reaction are hydrogen and methane. The coupling reaction of CH2 species was clearly facilitated by potassium. The effect of potassium was explained by the extended electron donation to adsorbed alkyl iodide in one hand, and by the direct interaction between potassium and I on the other hand.

Original languageEnglish
Pages (from-to)3736-3739
Number of pages4
JournalSurface Science
Volume601
Issue number18
DOIs
Publication statusPublished - Sep 15 2007

Fingerprint

Potassium
potassium
fragments
Surface reactions
dissociation
surface reactions
Ethylene
ethylene
X ray photoelectron spectroscopy
Thermal desorption spectroscopy
Electron energy loss spectroscopy
Methane
Iodides
products
methylene
iodides
spectroscopy
Hydrogen
Monolayers
methane

Keywords

  • Adsorption
  • Alkali promotion
  • Coupling reaction
  • Methylene iodide
  • Molybdenum carbide

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Condensed Matter Physics
  • Surfaces and Interfaces

Cite this

Effects of potassium on the reaction pathways of CH2 fragment over Mo2C/Mo(1 0 0). / Farkas, A. P.; Bugyi, L.; Koós, Á; Solymosi, F.

In: Surface Science, Vol. 601, No. 18, 15.09.2007, p. 3736-3739.

Research output: Contribution to journalArticle

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AU - Koós, Á

AU - Solymosi, F.

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N2 - The adsorption and surface reactions of CH2I2 on the K-dosed Mo2C/Mo(1 0 0) have been studied by high resolution electron energy loss spectroscopy, X-ray photoelectron spectroscopy and thermal desorption spectroscopy. Potassium is an effective promoter for the rupture of C-I bond in the adsorbed CH2I2. A partial dissociation of this compound occurred even at 100 K and was completed at 190 K at monolayer K coverage. The dissociation was further promoted by the illumination of coadsorbed layer at 100 K. As revealed by HREELS and XPS measurements the primary products of the dissociation are CH2 and I. Methylene was converted to π-bonded ethylene characterized by Tp = 160 K, and di-σ-ethylene with Tp = 350 K. Other products of the surface reaction are hydrogen and methane. The coupling reaction of CH2 species was clearly facilitated by potassium. The effect of potassium was explained by the extended electron donation to adsorbed alkyl iodide in one hand, and by the direct interaction between potassium and I on the other hand.

AB - The adsorption and surface reactions of CH2I2 on the K-dosed Mo2C/Mo(1 0 0) have been studied by high resolution electron energy loss spectroscopy, X-ray photoelectron spectroscopy and thermal desorption spectroscopy. Potassium is an effective promoter for the rupture of C-I bond in the adsorbed CH2I2. A partial dissociation of this compound occurred even at 100 K and was completed at 190 K at monolayer K coverage. The dissociation was further promoted by the illumination of coadsorbed layer at 100 K. As revealed by HREELS and XPS measurements the primary products of the dissociation are CH2 and I. Methylene was converted to π-bonded ethylene characterized by Tp = 160 K, and di-σ-ethylene with Tp = 350 K. Other products of the surface reaction are hydrogen and methane. The coupling reaction of CH2 species was clearly facilitated by potassium. The effect of potassium was explained by the extended electron donation to adsorbed alkyl iodide in one hand, and by the direct interaction between potassium and I on the other hand.

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