Ellipsometric Investigation of C60 Single Crystal

The optical properties of C60 fcc single-crystal are investigated for the first time in the 1.5–5 eV energy range by spectroscopic ellipsometry. The good quality of the samples allow a careful determination of the optical band gap at 1.72 eV. Optical and dielectric functions are directly obtained from the experimental data and compared with the results for isolated clusters and for thin films. The contribution of the optical transitions forbidden in the C60 cluster is discussed. Experimental findings are compared with available theoretical calculations.