Kinetics of oxygen induced delayed fluorescence of eosin adsorbed on alumina. The dependence on dye and oxygen concentrations

The kinetics of oxygen quenching of eosin (E) triplets adsorbed on alumina and concomitant 1O2 feedback-induced delayed fluorescence (DF) of E, were measured at different O2 and E concentrations by the diffuse-reflectance laser flash technique. The global kinetic analysis in terms of 1O2 feedback in which the energy transfer from 1O2 to 3E generates 1E∗ revealed the dependence of kinetic parameters on oxygen content and sample loading which matches the aggregation of E on the surface. The excitation migration in dye and oxygen manifolds is assumed to be involved resulting in high DF efficiency.