Studies of fullerenes by the excitation, emission, and scattering of electrons

This paper presents an overview of how electron spectroscopies have contrib uted to advances in fullerene research. In particular, we illustrate the vi tal role these techniques have played in improving our understanding of the importance of strong electronic correlation and of electron-phonon couplin g in these materials, in the derivation of electron hopping rates, in provi ding a direct determination of charge transfer and hybridisation in both fu llerene salts and adsorbed fullerenes and in determining the optical gap of these systems. We discuss systems of increasing complexity, starting with C-60 in the gas phase and in the solid state, and moving on to C-60 salts a nd to C-60 adsorbed on surfaces. Finally we look at both higher fullerenes and fullerenes with a heteroatom either on or inside the cage. (C) 1999 Els evier Science B.V. All rights reserved.