Excited State Absorption Study in Hematoporphyrin IX
Abbreviated Journal Title
Excited state absorption; Photodynamic therapy; Multiphoton absorption; Porphyrin; PORPHYRIN-BASED PHOTOSENSITIZERS; TIME-RESOLVED FLUORESCENCE; PHOTODYNAMIC THERAPY; CANCER-TREATMENT; QUANTUM YIELDS; SINGLET; SPECTROSCOPY; DYNAMICS; OXYGEN; FEMTOSECOND; Biochemical Research Methods; Chemistry, Analytical; Chemistry, Physical
We present the study of the excited state absorption of Hematoporphyrin IX dissolved in dimethyl sulfoxide. All measurements were carried out using open aperture Z-scan and white-light continuum pump-probe with picosecond pulses to avoid triplet excited state absorption. Without the latter contribution, the results obtained with both techniques show a transition to a high singlet excited state. The vibronic progression of the Q-band is observed due to photobleaching of the ground state. In addition, we show that the excited state presents reverse saturable absorption for most of the spectral range studied. A long relaxation component of the first singlet excited state was evidenced with the pump-probe experiment. This result is in agreement with fluorescence lifetime and fluorescence quantum yield measurements. In order to elucidate the origin of the nonlinear effects, we used a three-level energy diagram to describe the principal singlet-singlet transitions.
Journal of Fluorescence
"Excited State Absorption Study in Hematoporphyrin IX" (2010). Faculty Bibliography 2010s. 88.