Transient absorption of photoexcited titanylphthalocyanine in various molecular arrangements Original Research Article

Transient absorption of photoexcited titanylphthalocyanine (TiOPc) molecules in solids and in solution was investigated by means of the pump–probe absorption spectroscopy with picosecond and femtosecond time resolution. The differential absorption of solution was described by the absorption bleaching, excited state absorption and stimulated emission. The latter shifts to the long-wavelength side by ≈9 nm with 35±10 ps time constant. The differential absorption spectra of TiOPc solids show dominating bleaching of the absorption band components that are strongly shifted from the absorption band of molecules in solution, while the central part of the band is bleached very weakly. The contribution of the stimulated emission to the differential absorption is absent or very weak. These specific features are analyzed by discussing different models of the absorption band splitting.