OPTICAL-PROPERTIES OF C-60-BASED AND C-70-BASED SOLID FILMS

We review results obtained from our laboratory regarding the optical properties of C-60- and C-70-based thin solid films, including alkali metal (M) doped compounds. The films were deposited on various substrates (e.g. KBr, Si(100), quartz, Cu) by vacuum sublimation. First- and higher-order IR and Raman spectroscopies were used to determine values for most of the 46 intramolecular vibrational modes of the pristine solid, and the results are compared with theory. Doping (M)-induced shifts and splittings of these mode frequencies are also discussed. Finally, results of UV-visible-IR reflection-transmission spectroscopies and ellipsometry are presented which reveal structure in the dielectric function due to electronic absorption. For pristine C-60, the Clausius-Mossotti relation is used to extract the frequency-dependent molecular polarizability. Results from these studies of the electronic contribution to the optical dielectric function are discussed in connection with recent calculations.