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Phosphorescence is a type of photoluminescence related to fluorescence. When exposed to light (radiation) of a shorter wavelength, a phosphorescent substance will glow, absorbing the light and reemitting it at a longer wavelength. Unlike fluorescence, a phosphorescent material does not immediately reemit the radiation it absorbs.
Example of phosphorescence Monochrome monitor Aperture grille CRT phosphors. A phosphor is a substance that exhibits the phenomenon of luminescence; it emits light when exposed to some type of radiant energy.
A corollary of Kasha's rule is the Vavilov rule, which states that the quantum yield of luminescence is generally independent of the excitation wavelength. [4] [7] This can be understood as a consequence of the tendency – implied by Kasha's rule – for molecules in upper states to relax to the lowest excited state non-radiatively.
Phosphorescence, traditionally defined as persistent emission of light after the end of excitation. As the definition does not fully describe the phenomenon, quantum mechanics is employed where it is defined as there is a change in spin multiplicity from the state of excitation to the emission of light.
In phosphorescence, even if the emission lives several seconds, this is due to deexcitation between two electronic states of different spin multiplicity. Persistent luminescence involves energy traps (such as electron or hole traps) in a material, [ 4 ] which are filled during the excitation.
Pearl Scene using phosphorescent paint, Irving Berlin's 1921 Music Box Revue. Phosphorescent paint is commonly called "glow-in-the-dark" paint. It is made from phosphors such as silver-activated zinc sulfide or doped strontium aluminate, and typically glows a pale green to greenish-blue color. The mechanism for producing light is similar to ...
Becquerel's discovery of spontaneous radioactivity is a famous example of serendipity, of how chance favors the prepared mind. Becquerel had long been interested in phosphorescence, the emission of light of one color following the object's exposure to light
For example, the industrially important pentasodium triphosphate (also known as sodium tripolyphosphate, STPP) is produced industrially by the megatonne by this condensation reaction: 2 Na 2 HPO 4 + NaH 2 PO 4 → Na 5 P 3 O 10 + 2 H 2 O. Phosphorus pentoxide (P 4 O 10) is the acid anhydride of phosphoric acid, but several intermediates between ...