title: Excited state absorption study in hematoporphyrin IX.
abstract: 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.
authors.affiliation: Department of Chemistry, University of Central Florida, P.O. Box 162366, Orlando, FL 32816, USA.
authors.forename: Leonardo
authors.initials: L
authors.lastname: De Boni
authors.forename: Carlos
authors.initials: C
authors.lastname: Toro
authors.forename: Florencio E
authors.initials: FE
authors.lastname: Hernandez
mesh_terms: D000042:Absorption; D006415:Hematoporphyrins / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D013050:Spectrometry, Fluorescence; D013997:Time Factors
chemical_list: D006415:Hematoporphyrins