Optical properties of fullerite thin films in the 0.4 to 32 energy range

The optical properties of C60 thin films are investigated in the energy range 0.4 to 32 eV using reflectance, transmittance, and ellipsometric spectroscopies. The complex dielectric constant and the associated functions are determined by a combination of photometric and ellipsometric data and by Kramers-Kronig transformations. Spectral features above the fundamental absorption edge (at ≈ 1.8eV) are related to both one-electron interband transitions and collective electron effects. A comparison is made with recent results of electron energy loss spectroscopy and of theoretical calculations on the f.c.c. fullerite structure.