A photoluminescence study of C60 and C70

The luminescence spectra of C60 and C70 have been recorded in glassy toluene solution at 77 K and as neat solids at 5 K. The C70 spectrum consists of two band systems each with resolved vibronic structure. The red system of C70 begins at 15012 cm-1, exhibits a lifetime of 1 --> S0 fluorescence. The infrared emission system begins at 12614 cm-1, decays with a 30 ms lifetime and is assigned as T1 --> S0 phosphorescence. A weak luminescence maximum at 13579 cm-1 is assigned tentatively as the S1 --> S0 fluorescence of C60.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30243/1/0000638.pd

A PHOTOLUMINESCENCE STUDY OF C60C_{60} AND C70C_{70}

Author Institution: Department of Chemistry, The University of MichiganSince their discovery, there has been considerable interest in the spectroscopic characterization of fullerenes, in particular the $C_{60}$ (Buckminsterfullerene) and $C_{70}$ forms that may be produced in reasonable yields using a method described by Kratschmer et al. Arbogast et al. determined a number of important photophyscial properties of $C_{60}$ in hexane and benzene solutions, but were unable to detect either fluorescence or phosphorescence from $C_{60}$ at room temperature. However, a triplet state was detected by triplet-triplet transient absorption measurements, and photoquenching studies placed the triplet state energy between 11,500 and $14,500 cm^{-1}$. We have obtained luminescence spectra of $C_{60}$ and $C_{70}$ in glassy toluene solution at 77K and as neat solids at 5K. The $C_{70}$ spectrum consists of two band systems each with resolved vibronic structure. The red system of $C_{70}$ begins at $15,012 cm^{-1}$, exhibits a lifetime of $<20$ $\mu$sec and is assigned as $S_{1}\rightarrow S_{0}$ fluorescence. The infrared emission system begins at $12,614 cm^{-1}$, decays with a 30 msec. lifetime and is assigned as $T_{1}\rightarrow S_{0}$ phosphorescence. Several Raman modes are observed as combination bands in the infrared system. However, all of the prominent features cannot be assigned to a single, orbitally allowed transition."