Direct measurements of tetraphenylethylene torsional motion by picosecond spectroscopy
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We have investigated the time- and wavelength-resolved fluorescence of tetraphenylethylene (TPE) induced by 355-nm picosecond excitation in several solvents over a range of temperatures and viscosities. Several distinct fluorescence kinetic processes have been identified that are manifested by (i) time-dependent fluorescence spectral shifts, (ii) time-dependent fluorescent spectral-shape changes, and (iii) nonexponential fluorescence decay kinetics. It is found that the relaxation rates of these processes depend strongly on temperature and solvent viscosity. Two of the processes have rates that are greater than 1012 s-1 at room temperature. The observed fluorescence dynamics of TPE are complex and suggest that several channels are available for excited-state relaxation. We have tentatively assigned the relaxation pathways to radiative and radiationless electronic decay, vibrational relaxation, and two forms of excited-state conformational relaxation. A unified model is proposed for the photochemical dynamics of TPE. © 1981, American Chemical Society. All rights reserved.
author list (cited authors)
Barbara, P. F., Rand, S. D., & Rentzepis, P. M.
complete list of authors
Barbara, PF||Rand, SD||Rentzepis, PM