NONLINEAR BEHAVIOR IN THE OPTICAL-SPECTRA OF SOLID FULLERENE C-60

Optical emission spectra of solid C60 have been recorded at 1.9 K. Sev eral vibronic transitions are observed. In particular the dependence o f the emission spectrum with respect to the excitation intensity has b een studied at room temperature and at 12 K under excitation with 514. 5 nm and 488.0 nm laser radiation. The emission intensity increases wi th excitation intensity stronger than linear. At higher excitation pow ers an additional optical transition centered at 16 500 cm-1 becomes d ominant. In an absorption experiment in solution (1.4.10(-5) Mol/1), t he absorbed power of light is also nonlinear with respect to the excit ation power.