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 ...

light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 t ...

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 reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking ...

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 elect ...

, 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

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 Electrochemiluminescence or electrogenerated chemiluminescence (ECL) is a kind of luminescence produced during electrochemical reactions in solutions. In electrogenerated chemiluminescence, electrochemically generated intermediates undergo a highl ...

, a result of an electrochemical reaction **

Lyoluminescence Lyoluminescence refers to the emission of light while dissolving a solid into a liquid solvent. It is a form of chemiluminescence. The most common lyoluminescent effect is seen when solid samples which have been heavily irradiated by ionizing radi ...

, a result of dissolving a solid (usually heavily irradiated) in a liquid solvent **

Candoluminescence Candoluminescence is the light given off by certain materials at elevated temperatures (usually when exposed to a flame) that has an intensity at some wavelengths which can, through chemical action in flames, be higher than the blackbody emission ex ...

, is light emitted by certain materials at elevated temperatures, which differs from the blackbody emission expected at the temperature in question. * Crystalloluminescence, 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 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 emission resulting fro ...

, a result of an electric current passed through a substance **

Cathodoluminescence Cathodoluminescence is an optical and electromagnetic phenomenon in which electrons impacting on a luminescent material such as a phosphor, cause the emission of photons which may have wavelengths in the visible spectrum. A familiar example is ...

, a result of a luminescent material being struck by electrons *

Mechanoluminescence Mechanoluminescence is light emission resulting from any mechanical action on a solid. It can be produced through ultrasound, or through other means. * Fractoluminescence is caused by stress that results in the formation of fractures. * Piezolumi ...

, a result of a mechanical action on a solid **

Triboluminescence 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 ...

, 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 Piezoluminescence is a form of luminescence created by pressure upon certain solids. This phenomenon is characterized by recombination processes involving electrons, holes and impurity ion centres. Some piezoelectric crystals give off a certain amo ...

, produced by the action of pressure on certain solids **

Sonoluminescence Sonoluminescence is the emission of light from imploding bubbles in a liquid when excited by sound. History The sonoluminescence effect was first discovered at the University of Cologne in 1934 as a result of work on sonar. Hermann Frenzel ...

, 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. photo ...

, a result of absorption of photons **

Fluorescence Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, tha ...

, photoluminescence as a result of singlet–singlet electronic relaxation (typical lifetime: nanoseconds) **

Phosphorescence 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 fluo ...

, photoluminescence either as a result of triplet–triplet electronic relaxation or of

persistent luminescence Commonly referred as phosphorescence, persistent luminescence is the emission of light by a phosphorescent material after an excitation by ultraviolet or visible light. Such materials would "glow in the dark". Mechanism The mechanism underlying ...

(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 diode A light-emitting diode (LED) is a semiconductor Electronics, device that Light#Light sources, emits light when Electric current, current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy i ...

s (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 v ...

s, materials that emit light when irradiated by higher-energy

electromagnetic radiation In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic (EM) field, which propagate through space and carry momentum and electromagnetic radiant energy. It includes radio waves, microwaves, infrared, (visib ...

or particle radiation *Laser, and lamp industry *

Phosphor thermometry Phosphor thermometry is an optical method for surface temperature measurement. The method exploits luminescence emitted by phosphor material. Phosphors are fine white or pastel-colored inorganic powders which may be stimulated by any of a variety of ...

, measuring temperature using

phosphorescence 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 fluo ...

Thermoluminescence dating Thermoluminescence dating (TL) is the determination, by means of measuring the accumulated radiation dose, of the time elapsed since material containing crystalline minerals was either heated ( lava, ceramics) or exposed to sunlight ( sed ...

* Thermoluminescent dosimeter *Non-disruptive observation of processes within a cell. Luminescence occurs in some

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...

s when they are exposed to low-powered sources of

ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation ...

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of Light, visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from ...

(for example, portable UV lamps), at

atmospheric pressure Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, ...

and atmospheric temperatures. This property of these minerals can be used during the process of mineral identification at rock

outcrop An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. Features Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficia ...

s 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