Excited-state absorption spectroscopy of metallo-porphyrin dyes with both Q-and B-band excitation

Metallophthalocyanine and metallo-porphyrine derivatives, both of which have strong absorption band in the red/near-infrared (Q-band) and the blue/ultraviolet (B-band) spectral regions, were studied at 532 nm. With picosecond pulses, strong excited-state absorption was observed from the bottom of this manifold. On nanosecond time scales, this excited state may decay to a triplet state, or decay to the ground state. Due to the strong reverse-saturable absorber of these materials, excited-state absorption (ESA) and refraction at other wavelengths throughout the visible are also studied. The spectral behavior of the ESA depends on both the linear and excited-state spectra. The latter could be expected to be different for Q-band and B-band excitation