The difference between fluorescent and phosphorescent material is at the time of visible light emission
The fluorescence and phosphorescence are types of luminescence , or emission radiation which may be visible or not occurring and without the need for elevated temperatures and may be, for example, as a result of energy absorption of light.
- Fluorescent: A substance thus absorbs energy from the light provided by a particular source and emits visible radiation, however, when the power supply runs out, the emission of radiation stops immediately.
The name of this phenomenon came from the fact that it was observed in a mineral called fluor ita.
Examples:
* Traffic signs when they receive light from car headlights;
* Tracks on motoboys, garis and other workers’ uniforms ;
* Fluorescent lamp – it is internally coated by a phosphorous-based fluorescent material, so when the electric discharge occurs, this substance is excited by ultraviolet radiation (invisible to the human eye), producing visible light. The moment the lamp is turned off, the power output stops.
- Phosphorescent: Just as fluorescence occurs in phosphorescence, a substance emits visible radiation because it absorbs energy from the light provided by a particular source. However, in this case, even after the power supply has stopped, the phosphorescent substance continues for some time to emit visible light. This time can range from fractions of seconds to days.
This phenomenon was named because the phosphorous element and other materials are used in objects made to glow in the dark.
Examples:
* Some electrical outlets and switches are made of a plastic that gets added phosphorescent substances;
* Pointers to the wristwatch;
* Colored ribbon used at parties;
* Self-adhesive objects placed on the walls, especially in children’s rooms, such as stars and planets made of zinc sulphide.
But what about fireflies and jellyfish, like noctiluca, that are capable of producing light? In case it is fluorescence or phosphorescence?
Neither one nor the other, but bioluminescence . In this phenomenon occurs a chemical reaction in which the chemical energy is transformed into luminous energy and the living organism produces and emits cold light (unlike the incandescent lamps that produce heat).
In the case of fireflies and noctiluca, the production of light is mainly in the reaction in which an enzyme called luciferase oxidizes the substrate of the luciferin protein, 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 the light energy is absorbed from another source and then released; in bioluminescence light is produced by a chemical process independently from another source of light.
