Local field corrections for light absorption by fullerenes

With the aim of analysing measurements of absorption of electromagnetic rad iation by fullerene molecules in the gas phase, in liquid solution, and in solid films, we consider the classical problem of correction for enhancemen t of the local field due to polarisation of the medium. We argue that for c rystalline films the Clausius-Mossotti relation between the molecular polar isability and the dielectric function of the medium should bo reasonably ac curate, despite the fact that the polarised fullerene molecules are far fro m being point dipoles. For fullerene molecules in solution, the field deriv ed by Onsager from a cavity model should be a good approximation, and we di scuss and correct errors in earlier developments of this model. Owing to th e large polarisability of fullerenes, the local field corrections are very important, leading to large changes in the relative strength of absorption lines and also to small shifts in the positions: of these lines. Applicatio n of the corrections leads tu improved consistency between measurements in the gas phase: in solution, and in the solid.