List of light sources


This article lists sources of light, the visible part of the electromagnetic spectrum. It focuses on primary light sources rather than secondary light sources. Primary light sources produce photons from another energy source, such as heat, chemical reactions, or conversion of mass or a different frequency of electromagnetic radiation, and include light bulbs and stars like the Sun. Secondary light sources do not actually produce the light that comes from them.
A common and fundamental means of classifying primary light sources is on the basis of the mechanism of light emission. Light is generated when an electric charge undergoes acceleration, typically through incandescence or luminescence. Light from real light sources is often from a combination of mechanisms. Real light sources can in turn be categorised as anthropic or naturally occurring.

Incandescence

Incandescence is the emission of visible radiation due to the thermal excitation of atoms or molecules. It is thermal radiation, which emerges from the conversion of kinetic energy associated with heat, resulting in continuous spectra, which extend into the visible region when temperatures are sufficiently high. The lowest temperature at which thermal radiation is visible, known as the Draper point, is approximately.

Luminescence

Luminescence is any emission of light not ascribable directly to incandescence. One mechanism is atomic electron transition, which generally results in discrete spectra from tightly-bound core electrons. The similar mechanism of recombination involves loosely-bound or free electrons in the valence or conduction bands, and can result in continuous spectra from plasmas and optoelectronic semiconductor devices.
Many terms exist to describe different kinds of luminescence. Their meanings can overlap, and continue to evolve with time, sometimes leading to confusion. One recent example was the initial use of shrimpoluminescence to playfully describe shrimp-induced sonoluminescence.

Candoluminescence

Candoluminescence is light given off by certain materials at high temperatures that has an intensity at some wavelengths which can be higher than the blackbody emission expected from incandescence at the same temperature.

Cathodoluminescence

Cathodoluminescence is luminescence produced by the bombardment of a metal or a phosphor by electrons.

Chemiluminescence

Chemiluminescence is luminescence resulting from a chemical reaction.

Bioluminescence

Bioluminescence is light emitted by living organisms due to chemiluminescence.

Crystalloluminescence

Crystalloluminescence is luminescence during the process of crystallization, specifically during nucleation.

Cryoluminescence

Cryoluminescence is luminescence when an object is cooled or observable only at low temperatures.

Electrochemiluminescence

Electrochemiluminescence is luminescence resulting from an electrochemical reaction.
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Electroluminescence

Electroluminescence is luminescence caused by the action of an electric field in a gas or in a solid material. Electroluminescent materials can exhibit fluorescence, delayed fluorescence, and/or phosphorescence.
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Electric discharge

Electric discharge is the passage of an electric current through gases and vapours by the production and movements of charge carriers under the influence of an electric field. The ionized gas becomes a plasma. Such light sources exhibit electroluminescence; some may additionally exhibit photoluminescence and/or incandescence.
The following electric discharge sources exhibit electrostatic discharge:
The following list of electric discharge sources includes examples of gas-discharge or glow discharge lamps. To keep the list reasonably short, sources with only a small portion of optical radiation in the visible region and obsolete sources are not listed.
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Fluorescence and phosphorescence

Fluorescence and phosphorescence are typically associated with photoluminescence, but can apply to other kinds of luminescence as well.

Fluorescence

Fluorescence has traditionally been defined as luminescence which essentially occurs only during the irradiation of a substance by electromagnetic radiation. Any delay is typically limited to about 10 nanoseconds. However, some kinds of fluorescence, triplet-triplet annihilation delayed fluorescence ) exhibit delays akin to phosphorescence. To more clearly distinguish it from phosphorescence, fluorescence is more specifically defined as being due to an "allowed" transition generally from an excited singlet state to a ground singlet state. For brevity, the countless types of fluorescent materials that require energy from an external source are not listed here.

Phosphorescence

Phosphorescence has traditionally been defined essentially as fluorescence except with greater duration of emission following exposure to electromagnetic radiation. However, given the overlap with delayed fluorescence, phosphorescence is more specifically defined as luminescence involving a change in spin multiplicity, typically a "forbidden" transition from excited triplet state to ground singlet state.
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Mechanoluminescence

Mechanoluminescence is light resulting from mechanical stress, usually defined as being applied to a solid. Fractoluminescence, piezoluminescence, and triboluminescence are different kinds of mechanoluminescence.

Photoluminescence

Photoluminescence is light resulting from absorption of photons. The phenomenon is similar to radioluminescence, with overlapping meaning for high-energy electromagnetic radiation ; photoluminescent materials exhibit fluorescence, delayed fluorescence, and/or phosphorescence.
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Pyroluminescence

Pyroluminescence is light emitted by a gas or vapor excited by high temperature, as in a flame. At very high temperatures the collisions of atoms can cause ionization, in which case luminescence and incandescence become indistinguishable.

Radioluminescence and scintillation

Radioluminescence, also termed scintillation, is luminescence arising from excitation by high-energy particles or radiation. The phenomenon is similar to photoluminescence, with overlapping meaning for high-energy electromagnetic radiation ; scintillators exhibit fluorescence, delayed fluorescence, and/or phosphorescence.
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Sonoluminescence

Sonoluminescence is luminescence induced by sound waves, such as light emission resulting from imploding bubbles in a liquid.

Thermoluminescence

Thermoluminescence is luminescence resulting from an increase in temperature that releases trapped energy from a chemical reaction or previously absorbed radiation.

Other kinds of luminescence

Not all terms for different kinds of luminescence end in luminescence, or even orescence. Some additional types of luminescence involve acceleration of charged particles, including but not limited to electrons; notably, this can occur in a vacuum free of atoms. Cherenkov radiation is created when a charged particle moves faster than light in a given medium, similar to a sonic boom.
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Combined incandescence and luminescence

Light sources often exhibit both incandescence and luminescence.

Exothermic chemical reactions

Combustion is an exothermic chemical reaction that may or may not produce a flame or explosion. A flame provides visible evidence of combustion. Whereas incomplete combustion of methane can produce soot with a temperature sufficient to incandesce, its complete combustion yields the characteristic blue flame via luminescence, as can be demonstrated by adjusting a Bunsen burner. Methane burns in air at about ; a much higher temperature would be required to yield blackbody radiation with a similar bluish appearance.

Combustion-based lamps

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Other combustion-based light sources

Light sources associated with flames and pyrotechnics are limitless in number; those not used specifically to produce light are not listed.
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