OPTICAL-RESPONSE OF C-60 THIN-FILMS AND SOLUTIONS

We report the optical spectra of C-60 epitaxial films on mica with var ious thicknesses in the energy range from 1.4 eV to 6 eV, and for temp eratures from 13 K to 300 K. The transmittance of toluene, hexane, and heptane solutions of known concentrations has also been studied; a si gnificant shift of the absorption bands in these solvents has been fou nd. We fitted our spectra with Gauss-Lorentz (CL) line shapes to deter mine the energy positions, oscillator strengths, and widths of individ ual transitions. It has been found that the GL profiles excellently ap proximate the optical response. We compare the dielectric function of solid and molecular C-60 in detail, with special attention paid to the assignment of the forbidden and the lowest allowed transitions.