ELECTRIC FIELD EFFECTS ON ABSORPTION AND EMISSION SPECTRA OF END- PHENYLETHYNYLATED MESO-MESO LINKED PORPHYRIN ARRAYS IN A POLYMER FILM

摘要

External electric field effects both on absorption spectra and on fluorescence spectra of phenylethynylated meso-meso linked porphyrin arrays doped in a polymer film have been examined using electric field modulation spectroscopy with the number of the linked porphyrins from 1 to 4. The magnitude of the change in electric dipole moment (Δμ) and in molecular polarizability (Δα) was evaluated for excitation into each of the exciton splitting components of the Soret band and into each of the Q bands, and the results are compared with the meso-meso linked porphyrin arrays having no phenylethynyl substitutes. The non-zero value of Δμ shows that a photoinduced charge transfer occurs along the linked porphyrin array especially following excitation into the splitting component of the Soret band which gives the transition moment along the linked array. Field-induced quenching of fluorescence is also observed for phenylethynylated meso-meso linked porphyrin arrays in a PMMA film, suggesting that intramolecular nonradiative process(es) at the emitting state is sigmificantly enhanced by an electric field.