The temperature dependence of the fluorescence intensity and a nonradiative de-excitation process in sodium cryptand sodide

Abstract

To account for the strong temperature dependence of the photoluminescence intensity from sodium cryptand sodide, we introduce a spatially extended excitonic state into which exciton-polaritons can be scattered. The relevancy of such a state is discussed. By considering the exciton-polariton transport equation which includes the annihilation process for excitonpolaritons, we derive the dependence of the fluorescence intensity on temperature. It is shown that the annihilation process is completed very early during the time evolution of the excitonpolaritons, which is consistent with the experimental observation. The nonradiative transition of the spatially extended state is described in terms of a spherically symmetric lattice relaxation induced by the diffuse wavefunction of the spatially extended state. Continuum elasticity theory and variational principles are combined in an effort to find the electron-lattice coupling that is responsible for a polaron state in sodium cryptand sodide. Bartram and Stoneham's criterion is employed in establishing the maximum allowable speed of sound in sodium cryptand sodide.

The enhancement of luminescence in Co-doped cubic Eu2O3 using Li+ and Al3+ ions

“…A qualitatively similar argument for Na þ (C222)Na À to this kind of behavior was discussed in [20].…”

Effects of Temperature on Calcium-Sensitive Fluorescent Probes

“…A second important consideration when temperature is varied during the course of an experiment is the fact that the fluorescence itself is affected by temperature, regardless of binding characteristics. In general, quantum yield (Eastman and Rosa, 1968;Song et al, 1975;Cornelissen-Gude and Rettig, 1998;Haynes et al, 1993), and thus fluorescence intensity (Connors et al, 1998;Park, 1996;Law, 1994) both increase as temperature decreases, and, in polar solvents, the effect is even more pronounced (Waris et al, 1988; Bark and Force, 1993). In addition, excited-state lifetimes of fluorescent molecules are strongly affected by temperature, showing, in most cases, longer lifetimes at lower temperatures (Drain et al, 1998;Cornelissen-Gude and Rettig, 1998;Kumke et al, 1997;Young et al, 1997;van den Zegel et al, 1984).…”