QUANTUM EFFICIENCY STUDY OF PHOTOEXCITED STATES IN FULLERENES

We present a comparative study of photoluminescence (PL) and photoindu ced absorption (PA) excitation spectroscopy, resonant Raman (RR) spect roscopy and electroabsorption (EA) of C-60 and C-70 from 1.5 eV to 4.5 eV. In C-60 solid-state films, a salient feature at 2.3 eV was observ ed, which manifests itself as a peak in the PL excitation and RR spect ra, as an onset in the excitation spectra of charge carriers and tripl et excitons, and as the first prominent derivative feature in the EA s pectrum. In contrast, these features are absent in the case of isolate d C-60 molecules. We attribute the 2.3 eV feature to a charge transfer state in solid C-60. A similar charge transfer state was also observe d in solid C-70 at 2.15 eV.