THE fluorescence and the phosphorescence are types of luminescence, that is, from radiation emissions, which may or may not be visible and which occur without the need for high temperatures, which may be, for example, the result of the absorption of light energy.
- Fluorescent: such a substance absorbs light energy from a given source and emits visible radiation, however, when the power supply ends, the emission of radiation stops immediately.
The name of this phenomenon came from the fact that it was observed in a mineral called fluorineit.
Examples:
* Transit plates when they receive the light from car headlights;
* Bands on uniforms motorcycle couriers, street sweepers and other workers;
* Fluorescent lamp - it is internally coated with a phosphor-based fluorescent material, so when discharge occurs electrical, this substance is excited by ultraviolet radiation (invisible to the human eye), producing light visible. The moment the lamp is turned off, power emission stops.
- Phosphorescent: In the same way that occurs in fluorescence, in phosphorescence, a substance emits visible radiation because it absorbs energy from the light provided by a certain source. However, in this case, even after the power supply has stopped, the phosphor continues for some time to emit visible light. This time can vary from fractions of seconds to days.
This phenomenon got its name because the element phosphorusro and other materials are used in objects made to glow in the dark.
Examples:
* Some electrical outlets and switches they are made of a plastic that receives the addition of phosphorescent substances;
* clock hands of wrist;
* colored bracelets used at parties;
* sticky objects placed for decoration on the walls, mainly in children's rooms, such as little stars and planets made of zinc sulfide.
But what about fireflies and jellyfish, such as the noctiluca, which are capable of producing light? In their case, is it fluorescence or phosphorescence?
Neither one, but yes bioluminescence. In this phenomenon, a chemical reaction occurs in which chemical energy is transformed into light energy and the living organism produces and emits cold light (unlike incandescent bulbs which produce heat).
In the case of fireflies and noctilucas jellyfish, the production of light is mainly in the reaction in which an enzyme called luciferase oxidizes the luciferin protein substrate, consuming a molecule of ATP. The luciferin molecule, now energetically excited, releases this chemical energy in the form of light energy.
In all three cases (fluorescence, phosphorescence and bioluminescence), the light is cold, producing very little heat. However, while in fluorescence and phosphorescence, light energy is absorbed from another source and then released; in bioluminescence light is produced by a chemical process independently of another light source.
By Jennifer Fogaça
Graduated in Chemistry
Source: Brazil School - https://brasilescola.uol.com.br/quimica/diferenca-entre-fluorescente-fosforescente.htm
