C-60 TRIPLET LIFETIMES - VIBRATIONAL-ENERGY DEPENDENCE FROM 0 TO 80000 CM(-1)

The persistence of the lowest electronically excited state of C-60 has been studied in the vapor phase at temperatures near 1000 K. Populati on decay of this triplet state is found to be nonexponential, reflecti ng the thermal distribution of vibrational energies among the sample m olecules. The kinetic data can be quantitatively modeled by assuming a n exponential dependence of triplet-state lifetime on vibrational ener gy content. Extrapolation of these findings to lower vibrational energ ies accounts for previously reported C-60 triplet lifetimes measured i n condensed phases at temperatures down to 1 K. This study therefore p rovides a unified description of the 1000-fold variation in C-60 tripl et state lifetime over the 0-80000 cm(-1) range of vibrational energie s corresponding to temperatures between 0 and 1000 K.