PHOTO-PRODUCED DEFECT LUMINESCENCE IN SOLID C-60

We report changes in the photoluminescence (PL) spectra of solid C-60 crystals and films when exposed to low levels of visible laser radiati on. New PL features at 1.73 and 1.76 eV are seen to emerge at low temp eratures upon laser irradiation at low fluences in C-60 crystals grown from purified powder. In rapidly grown crystals, the 1.76 eV peak dom inates the PL spectrum. These new peaks are interpreted as the emissio n from metastable defects (X-traps) which are either photo-induced or produced during growth. In analogy with solid anthracene emission, the variations observed in the positions and relative intensities of the PL peaks in solid C-60 are thought to arise from differences due to th e presence of chemical impurities or physical imperfections, growth me thods, irradiation of light, temperature cycles, and strain in the cry stal.