Metallic-to-nonmetallic transition of Na coadsorbed with CO2 and H2O on the Cr2O3(111)/Cr(110) surface

C. A. Ventrice, D. Ehrlich, Eric Garfunkel, B. Dillmann, D. Heskett, H. J. Freund

Research output: Contribution to journalArticle

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Abstract

Coadsorption of Na with CO2 and H2O on a thin Cr2O3(111) single crystal epitaxially grown on a single-crystal Cr(110) substrate has been performed to study the effects of the coadsorbates on the electronic properties of the Na species. High-resolution electron-energy-loss spectroscopy spectra as a function of Na overlayer coverage reveal a continuous attenuation of the Fuchs-Kliewer surface-phonon loss modes with near total attenuation by ∼2 monolayers (ML). Coadsorption with either H2O or CO2 returns the substrate Fuchs-Kliewer modes to a relative intensity approximately equal to that observed on the clean Cr2O3(111) surface. Angle-resolved photoemission spectroscopy (ARPES) measurements from the Cr2O3(111) surface demonstrate almost total attenuation of the Cr2O3(111) valence-band emission by a Na coverage of ∼2 ML with no return of Cr2O3(111) valence-band emission features upon coadsorption. These observations provide strong evidence that the development of a metallic Na overlayer results in a damping of the coupling interaction between the electron and the Fuchs-Kliewer phonons and that upon reaction with the coadsorbed species, a uniform dielectric overlayer is formed which permits the return of the Fuchs-Kliewer losses. The metallic-to-nonmetallic transition of the overlayer is also supported by the ARPES data which reveal suppression of emission from the Fermi level, the disappearance of the LVV Auger transition, and a shifting to higher binding energy of the Na 2p emission upon compound formation during coadsorption.

Original languageEnglish
Pages (from-to)12892-12895
Number of pages4
JournalPhysical Review B
Volume46
Issue number19
DOIs
Publication statusPublished - 1992

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Photoelectron spectroscopy
Valence bands
attenuation
Monolayers
Single crystals
photoelectric emission
Electron energy loss spectroscopy
Substrates
Phonons
spectroscopy
Fermi level
Binding energy
valence
Electronic properties
single crystals
Damping
phonons
Electrons
energy dissipation
binding energy

ASJC Scopus subject areas

  • Condensed Matter Physics

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Metallic-to-nonmetallic transition of Na coadsorbed with CO2 and H2O on the Cr2O3(111)/Cr(110) surface. / Ventrice, C. A.; Ehrlich, D.; Garfunkel, Eric; Dillmann, B.; Heskett, D.; Freund, H. J.

In: Physical Review B, Vol. 46, No. 19, 1992, p. 12892-12895.

Research output: Contribution to journalArticle

Ventrice, C. A. ; Ehrlich, D. ; Garfunkel, Eric ; Dillmann, B. ; Heskett, D. ; Freund, H. J. / Metallic-to-nonmetallic transition of Na coadsorbed with CO2 and H2O on the Cr2O3(111)/Cr(110) surface. In: Physical Review B. 1992 ; Vol. 46, No. 19. pp. 12892-12895.
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abstract = "Coadsorption of Na with CO2 and H2O on a thin Cr2O3(111) single crystal epitaxially grown on a single-crystal Cr(110) substrate has been performed to study the effects of the coadsorbates on the electronic properties of the Na species. High-resolution electron-energy-loss spectroscopy spectra as a function of Na overlayer coverage reveal a continuous attenuation of the Fuchs-Kliewer surface-phonon loss modes with near total attenuation by ∼2 monolayers (ML). Coadsorption with either H2O or CO2 returns the substrate Fuchs-Kliewer modes to a relative intensity approximately equal to that observed on the clean Cr2O3(111) surface. Angle-resolved photoemission spectroscopy (ARPES) measurements from the Cr2O3(111) surface demonstrate almost total attenuation of the Cr2O3(111) valence-band emission by a Na coverage of ∼2 ML with no return of Cr2O3(111) valence-band emission features upon coadsorption. These observations provide strong evidence that the development of a metallic Na overlayer results in a damping of the coupling interaction between the electron and the Fuchs-Kliewer phonons and that upon reaction with the coadsorbed species, a uniform dielectric overlayer is formed which permits the return of the Fuchs-Kliewer losses. The metallic-to-nonmetallic transition of the overlayer is also supported by the ARPES data which reveal suppression of emission from the Fermi level, the disappearance of the LVV Auger transition, and a shifting to higher binding energy of the Na 2p emission upon compound formation during coadsorption.",
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N2 - Coadsorption of Na with CO2 and H2O on a thin Cr2O3(111) single crystal epitaxially grown on a single-crystal Cr(110) substrate has been performed to study the effects of the coadsorbates on the electronic properties of the Na species. High-resolution electron-energy-loss spectroscopy spectra as a function of Na overlayer coverage reveal a continuous attenuation of the Fuchs-Kliewer surface-phonon loss modes with near total attenuation by ∼2 monolayers (ML). Coadsorption with either H2O or CO2 returns the substrate Fuchs-Kliewer modes to a relative intensity approximately equal to that observed on the clean Cr2O3(111) surface. Angle-resolved photoemission spectroscopy (ARPES) measurements from the Cr2O3(111) surface demonstrate almost total attenuation of the Cr2O3(111) valence-band emission by a Na coverage of ∼2 ML with no return of Cr2O3(111) valence-band emission features upon coadsorption. These observations provide strong evidence that the development of a metallic Na overlayer results in a damping of the coupling interaction between the electron and the Fuchs-Kliewer phonons and that upon reaction with the coadsorbed species, a uniform dielectric overlayer is formed which permits the return of the Fuchs-Kliewer losses. The metallic-to-nonmetallic transition of the overlayer is also supported by the ARPES data which reveal suppression of emission from the Fermi level, the disappearance of the LVV Auger transition, and a shifting to higher binding energy of the Na 2p emission upon compound formation during coadsorption.

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