Luminescence is spontaneous emission of

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 te ...

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

chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

s, electrical energy, subatomic motions or stress on a crystal. This distinguishes luminescence from incandescence, 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, the emission of light as a result of a

** Bioluminescence, 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 Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference, as a measurable and quantitative phenomenon, and identifiable chemical change, with the potential difference as an outco ...

** Lyoluminescence, 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 A black body or blackbody is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. The name "black body" is given because it absorbs all colors of light. A black body ...

emission expected at the temperature in question. * Crystalloluminescence, produced during crystallization * Electroluminescence, a result of an electric current passed through a substance ** Cathodoluminescence, 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. * Piezolum ...

, 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, generated when bonds in certain crystals are broken by fractures ** Piezoluminescence, 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 an ...

, a result of imploding bubbles in a liquid when excited by sound * Photoluminescence, 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 Radioluminescence is the phenomenon by which light is produced in a material by bombardment with ionizing radiation such as alpha particles, beta particles, or gamma rays. Radioluminescence is used as a low level light source for night illumi ...

, a result of bombardment by ionizing radiation * Thermoluminescence, 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 Wulfenite is a lead molybdate mineral with the formula Pb Mo O4. It can be most often found as thin tabular crystals with a bright orange-red to yellow-orange color, sometimes brown, although the color can be highly variable. In its yellow form ...

)

Applications

Light-emitting diode A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (co ...

s (LEDs) emit light via electro-luminescence. * Phosphors, 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, (visible) li ...

or particle radiation *Laser, and lamp industry * Phosphor thermometry, 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 (sediment ...

Thermoluminescent dosimeter A thermoluminescent dosimeter, or TLD, is a type of radiation dosimeter, consisting of a piece of a thermoluminescent crystalline material inside a radiolucent package. When a thermoluminescent crystal is exposed to ionizing radiation, it abso ...

*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 visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

(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 Field may refer to: Expanses of open ground * Field (agriculture), an area of land used for agricultural purposes * Airfield, an aerodrome that lacks the infrastructure of an airport * Battlefield * Lawn, an area of mowed grass * Meadow, a grass ...

, 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