Proposed mechanism for the one photon one electron delayed fluorescence in some organic dyes

The one photon delayed fluorescence (DF), the excitation DF, the phosphorescence and the temperature dependence of these emissions in the cosin dye are published and discussed. The same experimental behavior is also observed in a series of dyes in various matrices at 77°K. To explain the primary photo-process, evidences are given in favor of a short-range electron phototransfer in the bulk of clusters formed by the contraction of the liquid solution followed by rigidification of the matrix. The recombination mechanism is also discussed in view of the experimental results.