Unusual triplet state relaxation in C60 oxide

The photophysics of C60O has been investigated. The calibrated UV–visible absorption spectrum, fluorescence quantum yield, and triplet–triplet absorption spectrum are compared to those of C60. Intrinsic triplet decay is anomalous, with typically weak temperature dependence below 180 K but unusual strong activation (EA=20 kJ mol−1) above. At 295 K, the triplet lifetime is only 4.2 μs, or 34 times shorter than that of C60. It is proposed that the activated decay channel involves reversible cleavage of the C–C epoxide bond. C60O efficiently quenches triplet C60 with a rate constant of 3.6×109 M−1 s−1.