Transient spectroscopy of excitons and polarons in C60 films from femtoseconds to milliseconds.

We have studied photoexcitations in C[sub 60] films using transient photomodulation and photoluminescence from 100 fs to 50 ms and absorption-detected magnetic resonance (ADMR). We show that singlet Frenkel excitons are the primary photoexcitations; their recombination kinetics in the picosecond time domain are dispersive as a result of inhomogeneity. The long-lived photoexcitations, however, are shown to be triplet excitons and charged polarons (C[sub 60][sup [minus plus]]), identified by the correlation found between their associated optical transitions and ADMR signals with spin 1 and 1/2, respectively.