The schematic presentation of pump-probe experiment. Figure 5. The absorption signal in such an experiment can be calculated as log(I0/It). The S(t) transient absorption signal can be computed by subtracting the absorption signal ΔA(t) measured with and without the pump pulse. For that reason the pump beam should be chopped. The typical measurement error of should be better than 10-3. ΔA Figure 6 presents the experimental setup. Figure 6. The schematic presentation of pump-probe experimental setup. III. UV-vis Absorption Spectroscopy of Phthalocyanines The aggregation has a direct influence on photophysical behavior of phthalocyanines, rendering normally active photosensitizers inactive through self-quenching. UV-vis absorption spectroscopy is ideally suited to monitor the aggregation of photosensitizers,a crucial factor for photodynamic phthalocyanines activity. Therefore, it is very important to discuss absorption properties of phthalocyanines. It is well known that phthalocyanines have two characteristic, strong and broad electronic bands: the Soret band in the near UV, and the Q band on the red side of the (π→π) (n→π*) spectrum.39 Figure 7 shows the electronic absorption spectra of zinc tetrasulfonated phthalocyanine tetrasodium salt (ZnPcS4) as a function of concentration in dimethyl sulfoxide (DMSO) and H2O solutions, respectively.
Figure 5. The schematic presentation of pump-probe experiment. The absorption signal S(t) in such an experiment can be calculated as log(I0/It). The transient absorption signal ΔA(t) can be computed by subtracting the absorption signal measured with and without the pump pulse. For that reason the pump beam should be chopped. The typical measurement error of ΔA should be better than 10-3. Figure 6 presents the experimental setup. Figure 6. The schematic presentation of pump-probe experimental setup. III. UV-vis Absorption Spectroscopy of Phthalocyanines The aggregation has a direct influence on photophysical behavior of phthalocyanines, rendering normally active photosensitizers inactive through self-quenching. UV-vis absorption spectroscopy is ideally suited to monitor the aggregation of photosensitizers,a crucial factor for photodynamic phthalocyanines activity. Therefore, it is very important to discuss absorption properties of phthalocyanines. It is well known that phthalocyanines have two characteristic, strong and broad electronic bands: the Soret band (π→π) in the near UV, and the Q band (n→π*) on the red side of the spectrum.39 Figure 7 shows the electronic absorption spectra of zinc tetrasulfonated phthalocyanine tetrasodium salt (ZnPcS4) as a function of concentration in dimethyl sulfoxide (DMSO) and H2O solutions, respectively.