PHOTOINDUCED LIGHT-ABSORPTION BY C-60 FILMS IN THE 0.08-4.0-EV SPECTRAL RANGE

Spectra of photoinduced light absorption in C-60 films at high and low excitations in the temperature range between 15 and 300 K have been m easured. In addition to the well-known explanation of photoinduced abs orption in terms of optical transitions in the system of photogenerate d singlet excitons, triplet excitons, and polarons, changes in the abs orption spectrum of the fullerite ground state must be considered. We suggest taking into account the effect of crystal field in explaining the features of the photoinduced absorption spectrum. A feature simila r to the inverted luminescence spectrum and ascribed to optical excita tion of singlet excitons, which is partially allowed owing to intermol ecular interaction, has been detected in spectrum of photoinduced abso rption. (C) 1997 American Institute of Physics.