Unusual triplet state relaxation in C-60 oxide

The photophysics of C60O has been investigated. The calibrated UV-visibIe a bsorption spectrum, fluorescence quantum yield, and triplet-triplet absorpt ion spectrum are compared to those of C-60. Intrinsic triplet decay is anom alous, with typically weak temperature dependence below 180 K but unusual s trong activation (E-A = 20 kJ mol(-1)) above. At 295 K, the triplet lifetim e is only 4.2 ps, or 34 times shorter than that of C-60. It is proposed tha t the activated decay channel involves reversible cleavage of the C-C epoxi de bond. C60O efficiently quenches triplet C-60 with a rate constant of 3.6 X 10(9) M-1 s(-1). (C) 1999 Elsevier Science B.V. All rights reserved.