Optical spectra of C 60 and C 70 complexes: their similarities and differences

Some possible uses of vibrational and electronic spectroscopies in characterising the basic interactions in C60 and C70 complexes are pointed out. We report on the wealth of infrared spectra of (usually) single crystals of C60 and C70 clathrates and complexes with organic donors. The changes in the spectral parameters of the complexes in comparison with those of the neutral fullerene molecules are attributed to redistribution of the charge on the spherical C60 or elongated C70 molecules in their compounds. Some general considerations on the origin of the IR, NIR, VIS and UV spectral variations are also given.