Abstract

Relaxation processes of bithiophene (2T), a model of technical interesting polythiophenes [1], were studied by pump-probe technique using two-photon excitation. Here we observed an unusually fast formation of triplets. The sample - solved in ethanol of 0.22M - was excited and probed at 400 nm using 650 fs frequency-doubled pulses from a regeneratively amplified mode-locked Ti:sapphire laser with a repetition rate of 2 Hz. Transient photoinduced changes in transmission were measured by photodiodes. The lowest allowed transition in 2T corresponds to 344 nm (3.60 eV). The fluorescence peak is located at 362 nm. We probed in a region where fluorescence and transient absorption mainly caused by triplets are located.

© 1998 IEEE