ELLIPSOMETRIC INVESTIGATION OF C-60 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 ellipso metry. The good quality of the samples allow a careful determination o f the optical band gap at 1.72 eV. Optical and dielectric functions ar e directly obtained from the experimental data and compared with the r esults for isolated clusters and for thin films. The contribution of t he optical transitions forbidden in the C60 cluster is discussed. Expe rimental findings are compared with available theoretical calculations .