Abstract :
We have investigated luminescence spectra, decay behaviors and their temperature dependence in C70 crystals prepared by different annealing procedures. The spectra have been measured with one-photon excitation, two-photon excitations and excitation below the HOMO–LUMO band gap. We have found two types of defect-related luminescence band with different activation energies: the radiative recombination of Frenkel-like excitons weakly localized at monomolecular-type defects existing near the sample surface and the radiative recombination of excitons trapped at bimolecular-type defects.
