Femtosecond pump-broadband probe study of primary doped polyaniline – The evidence of neutral primary photoexcitations

A film and a water solution of primary doped polyaniline were studied by means of femtosecond pump–probe spectroscopy in the 425–1050 nm spectral interval. Data at wavelengths from 425 to 650 nm were recorded for the first time. Primary photoexcitations created by pulses at 800 and 400 nm are treated as charge-transfer excitons in amorphous films and in globular aggregates of the solution. Ultrafast dynamics are interpreted as ∼1 ps exciton dissociation and formation of separate charge carriers. It was found that charged species cause specific spectral deformation and have a lifetime of about 7 ps.