Bonding nature of C60 adsorbed on Si(111) 7 × 7 and Si(100) 2 × 1 surfaces studied by HREELS and PES

S. Suto, K. Sakamoto, D. Kondo, Takanori Wakita, A. Kimura, A. Kakizaki

Research output: Contribution to journalArticle

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Abstract

We report here the measurements of vibrational excitation spectra, valence band spectra and C 1s core level spectra of C60 molecules adsorbed on Si(111) 7 × 7 and Si(100) 2 × 1 surfaces, using high-resolution electron energy loss spectroscopy (HREELS) and photoelectron spectroscopy (PES). At a coverage between 1 and 0.25 ML, HREELS and PES measurements show that the interaction is as weak as the van der Waals interaction on both surfaces. At a coverage lower than 0.25 ML, some contradictory results are obtained by HREELS and PES. With HREELS, the softening of several vibrational modes is observed on the Si(111) 7 × 7 surface, but no indication of softening is observed on the Si(100) 2 × 1 surface. The charge transfer scheme explains the softening well. These results by HREELS indicate that the nature of the bonding is ionic on the Si(111) 7 × 7 surface and of the van der Waals type on the Si(100) 2 × 1 surface. In contrast, the bonding states between C60 molecules and Si substrates are clearly observed at 2.4 eV on both surfaces with PES. The PES measurements indicate that the interaction has a covalent character on the Si(111) 7 × 7 surface, and that it is in between covalent and ionic, i.e. not purely ionic or at the covalent limit, on the Si(100) 2 × 1 surface. We will discuss the nature of the interaction manifested by HREELS and PES measurements in comparison with the spectra of C60 molecules adsorbed on metal surfaces.

Original languageEnglish
Pages (from-to)85-90
Number of pages6
JournalSurface Science
Volume427-428
DOIs
Publication statusPublished - Jun 1 1999
Externally publishedYes

Fingerprint

Electron energy loss spectroscopy
Photoelectron spectroscopy
energy dissipation
photoelectron spectroscopy
electron energy
high resolution
spectroscopy
softening
Molecules
interactions
molecules
Core levels
Valence bands
metal surfaces
vibration mode
indication
Charge transfer
charge transfer
Metals
valence

ASJC Scopus subject areas

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

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Bonding nature of C60 adsorbed on Si(111) 7 × 7 and Si(100) 2 × 1 surfaces studied by HREELS and PES. / Suto, S.; Sakamoto, K.; Kondo, D.; Wakita, Takanori; Kimura, A.; Kakizaki, A.

In: Surface Science, Vol. 427-428, 01.06.1999, p. 85-90.

Research output: Contribution to journalArticle

Suto, S. ; Sakamoto, K. ; Kondo, D. ; Wakita, Takanori ; Kimura, A. ; Kakizaki, A. / Bonding nature of C60 adsorbed on Si(111) 7 × 7 and Si(100) 2 × 1 surfaces studied by HREELS and PES. In: Surface Science. 1999 ; Vol. 427-428. pp. 85-90.
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