Dependence of the spontaneous emission of singlet oxygen on the refractive index and molecular polarizability of the surrounding dielectric media

The rate constants (k _r ) for singlet oxygen O₂ (a ¹Δ _g ) luminescence in several selected solvents and in binary solvent mixture (acetone-toluene) were measured. All data have been normalized such that k _r ^rel = 1.0 in toluene. It has been demonstrated that the changes in these rate constants were caused both by optical properties of a medium (the local field factor and density of photon states) and by an inherent property of the emitter of ¹O₂ (the square of transition moment). In its turn, the value of the transition moment is directly proportional to molecular polarizability of the medium molecules.