Abstract
The time-resolved photothermal methods are used in order to establish the yield of intersystem (singlet-triplet) crossing of dyes that are candidates for the application in photodynamic therapy. It is known that molecules with long living triplet state cause efficient photosensitization by direct interaction with the cells or by singlet oxygen generation.The steady state photoacoustic spectra enables one to establish the dye incorporation into cells.Both methods were applied to several phthalocyanines and the results gathered by photothermal measurements were compared with the results obtained by means of other methods.The six investigated dyes were compared.