OPTICAL-SPECTRA OF DIELS-ALDER ADDUCTS OF C-60

The UV-Vis spectra of Diels-Alder adducts of C-60 show characteristic differences with respect to the spectra of isolated C-60. New bands ap pear between 400 and 500 nm, as well as at around 700 nm. In order to explain the origin of these bands we performed quantum chemical calcul ations for model molecules: C60H2n (n=1,2,3). The upper bands correspo nd to singlet-singlet transitions while the lowest energy band can ori ginate only from a triplet level and spin dependent interactions shoul d be responsible for this excitation. Symmetry arguments indicate that such transitions remain forbidden for pure C-60.