Influence of surrounding dielectrics on the spontaneous emission of sulforhodamine B molecules

The spontaneous emission rate of molecules depends on the refractive index of the surrounding environment. We present a photoluminescence lifetime study of sulforhodamine B molecules dissolved in water droplets (inverted micelles) which are stabilized by a surfactant and suspended in solutions of different dielectric constants. A good agreement is found between the experimentally observed and theoretically expected lifetime variations. The radiative and nonradiative lifetimes of sulforhodamine B molecules in micelles are determined.