p-Dimethylaminobenzonitrile in polar solution. L Time-dependent rate in intramolecular electron transfer reaction

An experimental study in the pico- and nano-second range of the fluorescence of DMABN in propanol solution revealed for a large range of viscosities (20?3×10³cP) a non-exponential decay of the planar excited state disappearing by a twisted charge transfer state formation. These results have been analyzed by a theoretical model of electronic relaxation in the absence of a potential barrier, making evident a time dependence of the reaction rate which is confirmed by the analysis of the appearance of the CT state.