Intramolecular electron-transfer reaction in dimethylaminobenzonitrile

The fluorescence emission of dimethylaminobenzonitrile in polar solvents is analysed in terms of a model which is a microscopic generalization of the Grabowski two-level kinetic scheme. The ground and the lowest excited state are described by adiabatic potential surfaces, defined in terms of an internal torsional coordinate and a solvent polarization coordinate. The potential energy functions are given by the energy of the isolated molecule plus a contribution due to the electrostatic stabilization in the polar solvent. The interconversion process between the two minima of the potential surface corresponding to the excited singlet state, i.e. a planar state with a low dipole moment and a strongly polar charge transfer state, is described by a stochastic operator. The emission features are interpreted by a minimal set of parameters, both for radiative and non-radiative channels.