Triplet excitations of crystalline C60. An optically detected magnetic-resonance study in zero field

Abstract Upon excitation of a single crystal of C 60 in the visible, microwave transitions have been detected optically in zero field. The transitions derive from triplet states and their frequencies verify that these states are delocalized over more than one C 60 molecule, as previously inferred from EPR experiments. Different triplet states seem to correspond to excitations that are trapped in different domains of the crystal which indicates that structural or impurity-induced defects may be involved.