Morphology, structure, and electronic properties of Ce@C-82 films on Ag : Si(111)-(root 3x root 3)R30 degrees

• The adsorption behaviour and electronic properties of Ce@C-82 molecules on the Ag: Si(l I I)-(root3 x root3)R30degrees surface have been studied using scanning tunnelling microscopy and photoelectron spectroscopy. Submonolayer coverages and multilayer films of Ce@C-82 comprise highly ordered molecular domains which have a single, well-defined orientation with respect to the underlying substrate crystallographic axes. UPS spectra reveal that the Ce@C-82 films are semiconducting with a band gap of at least 0.3 eV and, as for La@C-82, contain low binding energy peaks related to charge transfer from the encapsulated atom to the fullerene molecular orbitals. The valence state of the incarcerated Ce has been probed by Ce 3d XPS for both 'as-deposited' and air-exposed Ce@C-82 monolayers. There is little change in the 'close to 3 +' valence state of the Ce atom-and little evidence of Cc oxidation-following exposure of a Ce@C-82 monolayer to atmosphere for a period of 10 months. (C) 2004 Elsevier B.V. All rights reserved.

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Nyckelord

scanning tunneling microscopy

fullerenes

photoemission (total yield)

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