Ultrafast excited state dynamics and dispersion studies of nonlinear optical properties in dinaphthoporphycenes

Abstract

Ultrafast excited state dynamics of dinaphthoporphycenes were investigated using femtosecond and picosecond degenerate pump-probe techniques at 600 nm and 800 nm, respectively. Femtosecond pump-probe data indicated photo-induced absorption at 600 nm resulting from two-photon/single photon excitation, whereas picosecond pump-probe data demonstrated photo-bleaching which was a consequence of three-photon absorption. The fastest lifetimes (100–120 fs) observed are attributed to the intramolecular vibrational relaxation, the slower ones (1–3 ps) to internal conversion, and the slowest components (7–10 ps) to non-radiative decay back to ground state. Z-scan studies in the 560–600 nm range were also carried out.