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

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 560-600nm range were also carried out. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3701274]