Unusually large stokes shifts and fluorescence decay times of the charge transfer fluorescence of electron-donor-acceptor-ion pairs - (Configuration transformation in the excited state)

Anomalously large Stokes shifts (10000 - 20000 cm(-1)) and fluorescence decay times (10(-4) - 10(-5) sec) of the charge transfer fluorescence of electron-donor-acceptor-ion pairs of methyl-pyridinium salts have been observed and interpreted as being the result of an intermolecular configuration transformation in the excited state. analogous to recently reported results of observations on weak n pi-EDA-complexes in the CT-excited state by means of ESR measurements [9].