Luminescence is

spontaneous emission Spontaneous emission is the process in which a quantum mechanical system (such as a molecule, an atom or a subatomic particle) transits from an excited energy state to a lower energy state (e.g., its ground state) and emits a quantized amount of ...

of light by a substance not resulting from heat; or "cold light". It is thus a form of cold-body

radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...

. It can be caused by chemical reactions,

electrical energy Electrical energy is energy related to forces on electrically charged particles and the movement of electrically charged particles (often electrons in wires, but not always). This energy is supplied by the combination of electric current and electr ...

, subatomic motions or stress on a crystal. This distinguishes luminescence from

incandescence Incandescence is the emission of electromagnetic radiation (including visible light) from a hot body as a result of its high temperature. The term derives from the Latin verb ''incandescere,'' to glow white. A common use of incandescence is ...

, which is light emitted by a substance as a result of heating. Historically, radioactivity was thought of as a form of "radio-luminescence", although it is today considered to be separate since it involves more than electromagnetic radiation. Chording mycobacterium tuberculesis culture

Chording mycobacterium tuberculesis culture

The dials, hands, scales, and signs of aviation and navigational instruments and markings are often coated with luminescent materials in a process known as "luminising".

Types

The following are types of luminescence: *

Chemiluminescence Chemiluminescence (also chemoluminescence) is the emission of light (luminescence) as the result of a chemical reaction. There may also be limited emission of heat. Given reactants A and B, with an excited intermediate ◊, : + -> lozenge -> ...

, the emission of light as a result of a chemical reaction **

Bioluminescence Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some b ...

, a result of biochemical reactions in a living organism ** Electrochemiluminescence, a result of an electrochemical reaction ** Lyoluminescence, a result of dissolving a solid (usually heavily irradiated) in a liquid solvent ** Candoluminescence, is light emitted by certain materials at elevated temperatures, which differs from the blackbody emission expected at the temperature in question. *

Crystalloluminescence Crystalloluminescence is the effect of luminescence produced during crystallization. The phenomenon was first reported in the 1800s from the rapid crystallization of potassium sulfate from an aqueous solution An aqueous solution is a solution i ...

, produced during

crystallization Crystallization is the process by which solid forms, where the atoms or molecules are highly organized into a structure known as a crystal. Some ways by which crystals form are precipitating from a solution, freezing, or more rarely deposi ...

Electroluminescence Electroluminescence (EL) is an optical phenomenon, optical and electrical phenomenon, in which a material emits light in response to the passage of an electric current or to a strong electric field. This is distinct from black body light emissi ...

, a result of an electric current passed through a substance ** Cathodoluminescence, a result of a luminescent material being struck by electrons * Mechanoluminescence, a result of a mechanical action on a solid ** Triboluminescence, generated when bonds in a material are broken when that material is scratched, crushed, or rubbed **

Fractoluminescence Triboluminescence is a phenomenon in which light is generated when a material is mechanically pulled apart, ripped, scratched, crushed, or rubbed (see tribology). The phenomenon is not fully understood, but appears to be caused by the separation a ...

, generated when bonds in certain crystals are broken by fractures ** Piezoluminescence, produced by the action of pressure on certain solids ** Sonoluminescence, a result of imploding bubbles in a liquid when excited by sound *

Photoluminescence Photoluminescence (abbreviated as PL) is light emission from any form of matter after the absorption of photons (electromagnetic radiation). It is one of many forms of luminescence (light emission) and is initiated by photoexcitation (i.e. photon ...

, a result of absorption of photons ** Fluorescence, photoluminescence as a result of singlet–singlet electronic relaxation (typical

lifetime Lifetime may refer to: * Life expectancy, the length of time a person is expected to remain alive Arts, entertainment, and media Music * Lifetime (band), a rock band from New Jersey * ''Life Time'' (Rollins Band album), by Rollins Band * ...

: nanoseconds) ** Phosphorescence, photoluminescence either as a result of

triplet A triplet is a set of three items, which may be in a specific order, or unordered. It may refer to: Science * A series of three nucleotide bases forming an element of the Genetic code * J-coupling as part of Nuclear magnetic resonance spectrosc ...

–triplet electronic relaxation or of persistent luminescence (typical lifetime: microseconds to hours) * Radioluminescence, a result of bombardment by ionizing radiation *

Thermoluminescence Thermoluminescence is a form of luminescence that is exhibited by certain crystalline materials, such as some minerals, when previously absorbed energy from electromagnetic radiation or other ionizing radiation is re-emitted as light upon h ...

, the re-emission of absorbed energy when a substance is heated **Cryoluminescence, the emission of light when an object is cooled (an example of this is wulfenite)

Applications

* Light-emitting diodes (LEDs) emit light via electro-luminescence. *

Phosphor A phosphor is a substance that exhibits the phenomenon of luminescence; it emits light when exposed to some type of radiant energy. The term is used both for fluorescent or phosphorescent substances which glow on exposure to ultraviolet or vi ...

s, materials that emit light when irradiated by higher-energy electromagnetic radiation or particle radiation *Laser, and lamp industry * Phosphor thermometry, measuring temperature using phosphorescence * Thermoluminescence dating * Thermoluminescent dosimeter *Non-disruptive observation of processes within a cell. Luminescence occurs in some minerals when they are exposed to low-powered sources of ultraviolet or infrared electromagnetic radiation (for example, portable UV lamps), at atmospheric pressure and atmospheric temperatures. This property of these minerals can be used during the process of mineral identification at rock outcrops in the field, or in the laboratory.

References

External links

Fluorophores.org A database of luminescent dyes
{{Authority control Light sources 1880s neologisms

Types

Applications

See also

References

External links