Nonmonotonic temperature dependence of fluorescence intensity of carbon dots in a glycerol solution

The effect of temperature on the fluorescence of carbon dot colloidal solution in glycerol has been studied. The dots were prepared by pyrolysis of a Nile Red laser dye using mesoporous silica as a template. It is established that the temperature dependence of the intensity of dominant emission peak is nontrivial: as the temperature of the solution rises, the initial quenching of the fluorescence is then replaced by its enhancement to the initial value. A three-level model of electronic states is considered, within which the observed temperature dependence of fluorescence is quantitatively described and the energies of nonradiative deactivation and activation of the emissive state are estimated. The nature of the electronic state responsible for the nonradiative activation of the emissive state is discussed. The possible influence of hydrogen bonds in the solute-solvent system on the tem-perature behavior of the CD fluorescence is also considered. A pronounced solvatochromic effect is noted in the fluorescence spectra of Nile Red based carbon dots in different solvents.

Automated summary

The influence of temperature on the fluorescence of carbon dot colloidal solution in glycerol was investigated. Carbon dots were synthesized via pyrolysis of Nile Red laser dye using mesoporous silica as a template. The temperature-dependent intensity of the dominant emission peak was found to be nontrivial: as the temperature increased, the initial fluorescence quenching was replaced by enhancement to the initial value. A three-level model of electronic states was employed to quantitatively describe the observed temperature dependence of fluorescence and estimate the energies of nonradiative deactivation and activation of the emissive state. The solvatochromic effect in the fluorescence spectra of Nile Red-based carbon dots in different solvents was also discussed.