Chapter 6 Effect of size and light power on the fluorescence yield of rubrene nanocrystals

Publisher Summary This chapter discusses the effect of size and light power on the fluorescence yield of rubrene nanocrystals. Rubrene nanocrystals exhibit a long-lived fluorescence in air. The crystal structure protects singlet states from oxygen. The surface of rubrene nanocrystals does not create quenching effects. A great interest is focused on nanosensors, because they can be cell-injected or transfected. In addition, the fluorescence decay curves are obtained with a time-correlated single-photon-counting method using a titanium–sapphire laser pumped by an argon ion laser. Absorption and fluorescent measurements on the colloidal dispersion of the nanoparticles of pigment are made difficult by their scattering and by local saturation of the absorption. The fluorescence photon is emitted in the crystal, and it has a good probability to go through that crystal. As the microcrystal size decreases, the fluorescence quantum yield increases. Moreover, for nanocrystals from the fluorescence lifetime of 16.4 ns, a fluorescence yield close to one can be expected.