Excitation energy dependence of the kinetics of charge-transfer formation

A derivative of DMABN is investigated in n-propanol at low temperature with respect to the excitation wavelength dependence of the stationary fluorescence and of the time-resolved fluorescence decay traces of the locally excited (LE) and charge transfer (CT) band. Shifting the excitation wavelength to the red enhances the CT band and accelerates the initial part of the nonexponential decay. The barrierless stochastic staircase model of Bagchi is used for interpretation. Within this model, long-wavelength excitation shifts the initial population closer to the region where the reaction occurs.