Adsorption of CO on Cs-precovered Ru(001)

formation of a double-layer structure Cs Cs + CO Ru and complete screening of the CO dipole

Hiroshi Kondoh, H. Nozoye

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Adsorption of CO on Cs-precovered Ru(001) with one-monolayer coverage (θCs = 0.33) has been investigated by means of electron energy loss spectroscopy (EELS), temperature-programmed desorption (TPD), low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). We found unusual adsorption of CO on the Cs(1 ML) Ru(001) surface. Gaseous CO adsorbs on the completely Cs-precovered surface at 85 K to a saturation coverage of 0.23. Although the low-resolution EELS and UPS results indicate that CO molecularly adsorbs on this surface, the CO stretching mode is not observed in the specular mode of high-resolution EELS but clearly appears at quite a low frequency of 1245 cm-1 in the off-specular mode. From a combination of the EELS, TPD and XPS experiments, we propose an adsorption model in which the CO molecules displace one-fourth of the Cs adatoms from the preadsorbed Cs monolayer, resulting in formation of a double-layer structure, Cs Cs + CO Ru(001); the displaced Cs atoms adsorb on the "rotated-p(2 × 2)" lattice which is composed of Cs and CO with a ratio of 1 : 1. In this adsorption state, it is considered that the CO species has an inclined or a side-on-bonded geometry and that the CO dipole is effectively screened by the second-layer Cs. This complete screening of the CO dipole is explained in terms of combined effects of the embedding of CO into the double-layer structure, a large polarizability of Cs and laterally delocalized electrons in the double-layer structure.

Original languageEnglish
Pages (from-to)39-54
Number of pages16
JournalSurface Science
Volume334
Issue number1-3
DOIs
Publication statusPublished - 1995 Jul 10
Externally publishedYes

Fingerprint

Electron energy loss spectroscopy
Carbon Monoxide
Screening
screening
energy dissipation
photoelectron spectroscopy
electron energy
Ultraviolet photoelectron spectroscopy
dipoles
Adsorption
adsorption
ultraviolet spectroscopy
Temperature programmed desorption
spectroscopy
Monolayers
X ray photoelectron spectroscopy
desorption
Adatoms
Low energy electron diffraction
embedding

Keywords

  • Alkali metals
  • Carbon monoxide
  • Chemisorption
  • Electron energy loss spectroscopy
  • Low-energy electron diffraction (LEED)
  • Ruthenium
  • Surface relaxation and reconstruction Thermal desorption spectroscopy
  • Vibrations of adsorbed molecules
  • Visible and ultraviolet photoelectron spectroscopy
  • X-ray photoelectron spectroscopy

ASJC Scopus subject areas

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

Cite this

Adsorption of CO on Cs-precovered Ru(001) : formation of a double-layer structure Cs Cs + CO Ru and complete screening of the CO dipole. / Kondoh, Hiroshi; Nozoye, H.

In: Surface Science, Vol. 334, No. 1-3, 10.07.1995, p. 39-54.

Research output: Contribution to journalArticle

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abstract = "Adsorption of CO on Cs-precovered Ru(001) with one-monolayer coverage (θCs = 0.33) has been investigated by means of electron energy loss spectroscopy (EELS), temperature-programmed desorption (TPD), low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). We found unusual adsorption of CO on the Cs(1 ML) Ru(001) surface. Gaseous CO adsorbs on the completely Cs-precovered surface at 85 K to a saturation coverage of 0.23. Although the low-resolution EELS and UPS results indicate that CO molecularly adsorbs on this surface, the CO stretching mode is not observed in the specular mode of high-resolution EELS but clearly appears at quite a low frequency of 1245 cm-1 in the off-specular mode. From a combination of the EELS, TPD and XPS experiments, we propose an adsorption model in which the CO molecules displace one-fourth of the Cs adatoms from the preadsorbed Cs monolayer, resulting in formation of a double-layer structure, Cs Cs + CO Ru(001); the displaced Cs atoms adsorb on the {"}rotated-p(2 × 2){"} lattice which is composed of Cs and CO with a ratio of 1 : 1. In this adsorption state, it is considered that the CO species has an inclined or a side-on-bonded geometry and that the CO dipole is effectively screened by the second-layer Cs. This complete screening of the CO dipole is explained in terms of combined effects of the embedding of CO into the double-layer structure, a large polarizability of Cs and laterally delocalized electrons in the double-layer structure.",
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N2 - Adsorption of CO on Cs-precovered Ru(001) with one-monolayer coverage (θCs = 0.33) has been investigated by means of electron energy loss spectroscopy (EELS), temperature-programmed desorption (TPD), low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). We found unusual adsorption of CO on the Cs(1 ML) Ru(001) surface. Gaseous CO adsorbs on the completely Cs-precovered surface at 85 K to a saturation coverage of 0.23. Although the low-resolution EELS and UPS results indicate that CO molecularly adsorbs on this surface, the CO stretching mode is not observed in the specular mode of high-resolution EELS but clearly appears at quite a low frequency of 1245 cm-1 in the off-specular mode. From a combination of the EELS, TPD and XPS experiments, we propose an adsorption model in which the CO molecules displace one-fourth of the Cs adatoms from the preadsorbed Cs monolayer, resulting in formation of a double-layer structure, Cs Cs + CO Ru(001); the displaced Cs atoms adsorb on the "rotated-p(2 × 2)" lattice which is composed of Cs and CO with a ratio of 1 : 1. In this adsorption state, it is considered that the CO species has an inclined or a side-on-bonded geometry and that the CO dipole is effectively screened by the second-layer Cs. This complete screening of the CO dipole is explained in terms of combined effects of the embedding of CO into the double-layer structure, a large polarizability of Cs and laterally delocalized electrons in the double-layer structure.

AB - Adsorption of CO on Cs-precovered Ru(001) with one-monolayer coverage (θCs = 0.33) has been investigated by means of electron energy loss spectroscopy (EELS), temperature-programmed desorption (TPD), low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). We found unusual adsorption of CO on the Cs(1 ML) Ru(001) surface. Gaseous CO adsorbs on the completely Cs-precovered surface at 85 K to a saturation coverage of 0.23. Although the low-resolution EELS and UPS results indicate that CO molecularly adsorbs on this surface, the CO stretching mode is not observed in the specular mode of high-resolution EELS but clearly appears at quite a low frequency of 1245 cm-1 in the off-specular mode. From a combination of the EELS, TPD and XPS experiments, we propose an adsorption model in which the CO molecules displace one-fourth of the Cs adatoms from the preadsorbed Cs monolayer, resulting in formation of a double-layer structure, Cs Cs + CO Ru(001); the displaced Cs atoms adsorb on the "rotated-p(2 × 2)" lattice which is composed of Cs and CO with a ratio of 1 : 1. In this adsorption state, it is considered that the CO species has an inclined or a side-on-bonded geometry and that the CO dipole is effectively screened by the second-layer Cs. This complete screening of the CO dipole is explained in terms of combined effects of the embedding of CO into the double-layer structure, a large polarizability of Cs and laterally delocalized electrons in the double-layer structure.

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KW - Surface relaxation and reconstruction Thermal desorption spectroscopy

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