TRIPLET EXCITED-STATE BEHAVIOR OF FULLERENES - PULSE-RADIOLYSIS AND LASER FLASH-PHOTOLYSIS OF C-60 AND C-70 IN BENZENE

Both pulse radiolysis and laser flash photolysis techniques have been employed to characterize the triplet excited state behavior of C60 and C70 in benzene at 296 K. Apart from the previously reported absorption in the visible, we were able to characterize its absorption in the UV region and determine the extinction coefficients in the visible region. Pulse radiolysis experiments give indirect confirmation for the spectral features of the triplet excited states. Self-quenching processes such as the ground-state quenching (2 x 10(8) M-1 s-1 for C-3(60)* and 6 x 10(8) M-1 s-1 for C-3(70)*) and triplet-triplet annihilation (2k = 1.8 x 10(9) M-1 s-1 for C-3(60)* and 2k = 2 x 10(9) M-1 s-1 for C-3(70)*) can lead to the rapid deactivation of the triplet excited state.