OPTICAL-PROPERTIES OF FULLERITE THIN-FILMS IN THE 0.4 TO 32EV ENERGY-RANGE

The optical properties of C60 thin films are investigated in the energ y range 0.4 to 32 eV using reflectance, transmittance, and ellipsometr ic spectroscopies. The complex dielectric constant and the associated functions are determined by a combination of photometric and ellipsome tric data and by Kramers-Kronig transformations. Spectral features abo ve the fundamental absorption edge (at almost-equal-to 1.8 eV) are rel ated to both one-electron interband transitions and collective electro n effects. A comparison is made with recent results of electron energy loss spectroscopy and of theoretical calculations on the fc.c. fuller ite structure.