Dynamic process in a hexameric benzo-porphyrin studied by femtosecond transient absorption

The fast kinetics of a hexameric benzo-porphyrin compound was investigated by femtosecond transient absorption spectroscopy. Using polychromatic detection, a sequence of spectra acquired at different delays revealed complex kinetic processes on the timescale of approximately 20 ps. The samples were then investigated at selected wavelengths by using a dual-colour femtosecond pump–probe setup. The same sequence of measurements was carried out under identical conditions on a benzo-porphyrin model sample. The comparison of the transient absorption decays recorded for both compounds revealed that only in the hexamer a 20 ps decay component is present which is attributed to an intramolecular interchromophoric excited-state process.