Pophyrin derivatives investigated by means of electronic spectroscopy. The substituted porphyrins are not planar and therefore exhibit configurational variants with respect to bending and/or torsional angles of the substituents. The synthesis of TPP is known to be accompanied by minor contributions of TPC (not shown) with one of the four pyrrole-rings replaced by a pyrroline-ring.
(Top panel) Fluorescence excitation spectrum of porphyrin in helium droplets. (Bottom panel) Dispersed emission spectrum of porphyrin in helium droplets with inverted wavenumber scale. The center abscissa is scaled to the common origin at 16 312.4 cm−1 and allows for directly reading of vibrational wavenumbers.
Electronic origin of the fluorescence excitation spectrum of porphyrin in helium droplets recorded with a pulsed laser system (top panel) reproduced from Ref. 9 and with the cw setup (bottom panel).
Electronic origins of porphyrin derivatives in helium droplets as indicated. Each panel shows the spectrum recorded with the cw setup (red line) and the pulsed setup (black line). The wavenumber is counted from the corresponding origin whose absolute value is given in each panel.
A second origin identified in the fluorescence excitation spectrum of a TMP sample recorded with the cw setup. The corresponding molecular species could not be identified.
(Top panel) Fluorescence excitation spectrum of TPC recorded by means of the pulsed setup. (Bottom panel) Dispersed emission spectrum of TPC recorded upon excitation at the electronic origin. The second trace is the same spectrum magnified by a factor of 7 in the intensity and shifted upwards.
Fluorescence excitation spectra of the electronic origin of TPC recorded with the cw setup at low (black line) and high (red line) laser intensity. The blue spectrum is taken from Fig. 6 and was recorded with the pulsed setup. The photon flux increases from black to red to blue. For details, see text.
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