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Fluorescence is the phenomenon of absorption of electromagnetic radiation, typically from ultraviolet or visible light, by a molecule and the subsequent emission of a photon of a lower energy (smaller frequency, longer wavelength). This causes the light that is emitted to be a different color than the light that is absorbed.
Micrograph of paper autofluorescing under ultraviolet illumination. The individual fibres in this sample are around 10 μm in diameter.. Autofluorescence is the natural fluorescence of biological structures such as mitochondria and lysosomes, in contrast to fluorescence originating from artificially added fluorescent markers (fluorophores).
Similarly, color is due to the energy absorbed by the compound, when an electron transitions from the HOMO to the LUMO. Lycopene is a classic example of a compound with extensive conjugation (11 conjugated double bonds), giving rise to an intense red color (lycopene is responsible for the color of tomatoes).
Color chips or color samples from a plastic pellet manufacturer that enables customers to evaluate the color range as molded objects to see final effects. A color chart or color reference card is a flat, physical object that has many different color samples present. They can be available as a single-page chart, or in the form of swatchbooks or ...
Atomic Fluorescence Spectroscopy (AFS) techniques are useful in other kinds of analysis/measurement of a compound present in air or water, or other media, such as CVAFS which is used for heavy metals detection, such as mercury. Fluorescence can also be used to redirect photons, see fluorescent solar collector.
A simplified Jablonski diagram illustrating the change of energy levels.. The principle behind fluorescence is that the fluorescent moiety contains electrons which can absorb a photon and briefly enter an excited state before either dispersing the energy non-radiatively or emitting it as a photon, but with a lower energy, i.e., at a longer wavelength (wavelength and energy are inversely ...
Fluorescence of different substances under UV light. Green is a fluorescein, red is Rhodamine B, yellow is Rhodamine 6G, blue is quinine, purple is a mixture of quinine and rhodamine 6g. Solutions are about 0.001% concentration in water. Fluorophore molecules could be either utilized alone, or serve as a fluorescent motif of a functional system.
The color of its aqueous solutions is green by reflection and orange by transmission (its spectral properties are dependent on pH of the solution), [2] as can be noticed in bubble levels, for example, in which fluorescein is added as a colorant to the alcohol filling the tube in order to increase the visibility of the air bubble contained ...