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The surface core-level shift in C 1s soft x-ray photoemission spectroscopy has been experimentally observed in films of C 60 on Al. A value of 0.100Ϯ0.025 eV has been determined. Theoretical calculations are presented which show that the core hole is uniformly screened by the C 60 molecule, and that the effect of the surface upon this intramolecular screening should be negligible. The observed SCLS can therefore be accounted for by the difference in final state ͑core hole ϩ polarized near-neighbor molecules͒ between bulk and near-surface atoms, as calculated by a straightforward, real-space, local-field calculation.

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The C1s core photoelectron shakeup spectrum of fullerene has been studied experimentally and theoretically, as well as the corresponding spectra of the smaller model compounds acenaphthylene and naphthalene. It is found that many of the shakeup excitations of C60 can be classified in terms of excitations found in the model compounds. A population analysis of the orbitals involved reveals a systematic behavior, enabling a generalization to extended aromatic systems and to an infinite graphite layer.

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