Spectroscopic study of singlet oxygen photogeneration in meso-tetra-sulphonatophenyl-porphin

Meso-tetra(4-sulphonatophenyl)porphin (TPPS4) is commonly used as a photosensitiser in photodynamic therapy. In this contribution, we have studied the dependence of singlet oxygen photogeneration by TPPS4 in buffer on concentration and pH. From the obtained two-dimensional matrix of data (phosphorescence intensity as a function of time and wavelength) we determined lifetimes of the photosensitiser triplet state together with those belonging to both the rise and decay of the singlet oxygen emission. Excitation quenching was studied and discussed within a wide range of concentrations.