Optical spectroscopy of C60 complexes

Complexes of fullerene C60 with different organic donors have been studied by optical absorption spectroscopy in solutions and in solid state. Charge transfer bands were found for C60 complexes with tetrathiafulvalenes, pyranylidene and xantenyl in the 600–1300 nm range. It is shown that the energies corresponding to the maxima of charge transfer bands (hvct) for C60 complexes in solution are almost independent of solvent polarity. The hvCT values for the complexes in solid state are ~0.15–0.20 eV less than in solution. The dependence of the hvCT values on donor ionization potentials (Ip) for C60 complexes with tetrathiafulvalenes in solid state was found to be hvCT= 0.82 ip–3.93 eV. The lowering of the intensity was observed for the C60 transitions at 420–540 nm in absorptoin spectra of single crystals of some C60 complexes obviously due to isolation of C60 molecules.