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Fluorescence intermittency, or blinking, is the phenomenon of random switching between ON (bright) and OFF (dark) states of the emitter under its continuous excitation. It is a common property of the nanoscale emitters (molecular fluorophores , colloidal quantum dots ) related to the competition between the radiative and non-radiative ...
The bonding in certain cadmium-free quantum dots, such as III–V-based quantum dots, is more covalent than that in II–VI materials, therefore it is more difficult to separate nanoparticle nucleation and growth via a high temperature dual injection synthesis.
Another application of this technique involves using Zinc Sulfide quantum dots to treat industrial waste water. [19] Indium An alternative to the heavy metal quantum dots are quantum dots that contain Indium. One example is the use of CuInS2 quantum dots as fluorescent labels that emit light in the near infrared region of the visible spectrum. [20]
Graphene quantum dots (GQDs) are graphene nanoparticles with a size less than 100 nm. Due to their exceptional properties such as low toxicity, stable photoluminescence , chemical stability and pronounced quantum confinement effect, GQDs are considered as a novel material for biological, opto-electronics, energy and environmental applications.
Some authors have provided evidence of size-dependent fluorescence properties, suggesting that the emission arises from electronic transitions with the core of the dots, influenced by quantum confinement effects, [10] [11] whereas other works, including single particle measurements, [12] have rather attributed the fluorescence to recombination ...
Schematic of SPDC process. Note that conservation laws are with respect to energy and momentum inside the crystal.. Spontaneous parametric down-conversion (also known as SPDC, parametric fluorescence or parametric scattering) is a nonlinear instant optical process that converts one photon of higher energy (namely, a pump photon) into a pair of photons (namely, a signal photon, and an idler ...
The effect of EIT on a typical absorption line. A weak probe normally experiences absorption shown in blue. A second coupling beam induces EIT and creates a "window" in the absorption region (red). This plot is a computer simulation of EIT in an InAs/GaAs quantum dot
Thus, the fluorescence quantum yield is affected if the rate of any non-radiative pathway changes. The quantum yield can be close to unity if the non-radiative decay rate is much smaller than the rate of radiative decay, that is k f > k nr. [2] Fluorescence quantum yields are measured by comparison to a standard of known quantum yield. [2]