Photoluminescence of nano-scal fullerene (C₆₀) aggregates in a solvent mixture

We present the photoluminescence emission of C₆₀ aggregates in benzene-ethanol mixtures of different compositions. For ethanol volume fractions in the solvent mixture less than 50 %, the photoluminescence spectra show the spectral shape of aggregates at 120 K. A change in the spectral shape of the photoluminescence emission due to the formation of C₆₀ aggregates at the liquid-solid transition temperature of the solvent mixture, as in the case of a single solvent (benzene, toluene, or CS₂), is reported. The shift in the 0-0 transition energy to a high energy in comparison with the C₆₀ crystal is noticed. The 0-0 transition energy for a high ethanol volume fraction of the solvent mixture (>70 %) shows no shift and is located at almost the same region as that of C₆₀ crystal photoluminescence spectrum. Sizes of the C₆₀ aggregates in the mixture of benzene-ethanol with a high ethanol volume fraction much bigger than those of C₆₀ aggregates in single crystals (>2.3 nm in benzene) is reported.