Lifetimes of the lowest triplet state of the two most stable fullerenes, Csa and &a, were measured in a supersonic beam by twocolor resonant two-photon ionization. When prepared by intersystem crossing from the singlet manifold, excited at 4.03 eV, these triplet states were found to have lifetimes of 42 and 41 us, respectively. The energies of these triplet states (1.7 and 1.6 eV, respectively) were measured by photoelectron spectroscopy of the corresponding negative ions
