(C{sub 6}H{sub 5}){sub 5}C{sub 60}H at Si(111)-(7x7) and Ag:Si(111)-({radical}(3)x{radical}(3))R30 deg. surfaces

Journal Article · Mon Aug 15 00:00:00 EDT 2005 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.72.075426· OSTI ID:20719342

Phillips, M A; O'Shea, J N; Moriarty, P ^[1]; Birkett, P R ^[2]; Purton, J ^[3]; Kroto, H W; Walton, D R.M.; Taylor, R ^[4]

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1. School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)
2. Department of Chemistry and Materials, Manchester Metropolitan University, Manchester M15 6BH (United Kingdom)
3. Daresbury Laboratory, Warrington WA4 4AD (United Kingdom)
4. Fullerene Science Centre, University of Sussex, Brighton BN1 9RH (United Kingdom)

We have studied the properties of (C{sub 6}H{sub 5}){sub 5}C{sub 60}H in thick film form and adsorbed at two surfaces at the extremes of chemical reactivity - the highly reactive Si(111)-(7x7) and chemically passivated Ag:Si(111)-({radical}(3)x{radical}(3))R30 deg. surfaces - using photoemission spectroscopy (PES) and near-edge x-ray fine structure (NEXAFS) spectroscopy. Our results show that the phenyl groups produce dramatic changes in the electronic structure of the fullerene system, including a lifting of the degeneracy of electronic states and a widening of the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) bandgap, resulting in changes in the chemistry of the fullerene cage itself. The modification of the fullerene in this way also enhances the polarisation screening effect observed in fullerene systems. Adsorption at the Si(111)-(7x7) and Ag:Si(111)-({radical}(3)x{radical}(3))R30 deg. surfaces is mediated by two different mechanisms, the former involving formation of covalent bonds, and the latter largely van der Waals in character. Despite the lack of a strong chemical interaction, however, a 0.9 ML coverage of (C{sub 6}H{sub 5}){sub 5}C{sub 60}H on Ag:Si(111)-({radical}(3)x{radical}(3))R30 deg. leads to a shift of the Si 2p core-level spectrum by {approx}200 meV to higher binding energy, suggesting that a positive interface dipole contributes to the adsorption energy of the fullerene at this surface.

• OSTI ID: 20719342
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 72, Issue 7; Other Information: DOI: 10.1103/PhysRevB.72.075426; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION SPECTROSCOPY
ADSORPTION
BINDING ENERGY
COVALENCE
DIPOLES
ELECTRON SPECTRA
ELECTRONIC STRUCTURE
ENERGY LEVELS
FILMS
FINE STRUCTURE
FULLERENES
INTERFACES
LAYERS
MOLECULAR ORBITAL METHOD
PASSIVATION
PHOTOELECTRON SPECTROSCOPY
PHOTOEMISSION
POLARIZATION
SILICON
SILVER
SURFACE ENERGY
SURFACES
VAN DER WAALS FORCES
X-RAY SPECTROSCOPY