Effect of protonation on the singlet–singlet excited-state absorption of meso-tetrakis(p-sulphonatophenyl) porphyrin

Excited-state absorption investigation of a cationic porphyrin derivative

“…6 depicts the singlet excited-state absorption cross-section together with the ground-state crosssection, indicating that they have similar shapes at the Q-band region. As previously reported [27], this is a typical behavior for porphyrins with D 2h symmetry, like the free bases, and indicates that the porphyrin vibronic structure remains practically unchanged upon excitation. Such result is supported by the small Stokes shift presented by the fluorescence emission.…”

“…Owing to the group velocity dispersion, the bluer intrapulse components are approximately 4 ps delayed in respect to those in the red. This procedure was performed in a theoretical fitting, in order to compensate possible accumulative contributions from excited-state absorption [27,28]. In the Z-scan experiments the sample was placed in a 0.2 cm optical cell in order to assure the thin sample approximation.…”

“…The ground-state absorption cross-section is obtained from the linear absorbance spectra and then, the only parameter used for the fitting of the Z-scan data is the singlet excited-state absorption cross-section. It is significant to mention that any contribution of cumulative processes, caused by the white-light pulse chirp, is taken into account in the fitting procedure, considering the time dependence of the whitelight components [27,28]. Fig.…”

Effects of environment on the photophysical characteristics of mesotetrakis methylpyridiniumyl porphyrin (TMPyP)

“…The interaction of porphyrin with environment and with natural or synthetic nano-organized structures, such as cell membranes, micelles and bio-and synthetic polymers greatly affects its electronic structure and, as a consequence, modifies its excited-state characteristics [10][11][12][13][14][15][16][17]. Although a large number of porphyrins with different side groups has been synthesized lately, further study of simple symmetric porphyrins continues to be of interest.…”

Laser induced protonation of free base porphyrin in chloroform results in the enhancement of positive nonlinear absorption due to conformational distortion

“…Moreover, the ratio of the excited to ground state absorption cross-section increases upon protonation [3,[4][5][6][7]. The latter change is especially desirable for application in passive optical limiting (OL) devices [8,9].…”