Luminescence (Wiki)
From Wikipedia, the free encyclopedia
Luminescence is emission of light by a substance not resulting from heat; it is thus a form of cold body radiation. It can be caused bychemical reactions, 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. The term 'luminescence' was introduced in 1888 by Eilhard Wiedemann.[1][2]
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'.
The following are types of luminescence
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Chemiluminescence, a result of a chemical reaction
- Bioluminescence, emission as a result of biochemical reaction by a living organism
- Electrochemiluminescence, a result of an electrochemical reaction
- Crystalloluminescence, produced during crystallization
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Electroluminescence, a result of an electric current passed through a substance
- Cathodoluminescence, a result of a luminescent material being struck by the electrons
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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, generated when bonds in certain crystals are broken by fractures
- Piezoluminescence, produced by the action of pressure on certain solids[3]
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Photoluminescence, a result of absorption of photons
- Fluorescence, photoluminescence as a result of singlet–singlet electronic relaxation (typical lifetime: nanoseconds)
- Phosphorescence, photoluminescence as a result of triplet–singlet electronic relaxation (typical lifetime: milliseconds to hours)
- Radioluminescence, a result of bombardment by ionizing radiation
- Sonoluminescence, a result of imploding bubbles in a liquid when excited by sound
- Thermoluminescence, the re-emission of absorbed light when a substance is heated
Applications
- Light-emitting diodes (LEDs) emit light via electro-luminescence
- Phosphors, emitting light when irradiated by higher-energy electromagnetic radiation or particle radiation
- Phosphor thermometry, measuring temperature using phosphorescence
References
- ^ E. Wiedemann (1888) "Über Fluorescenz und Phosphorescenz, I. Abhandlung" (On fluorescence and phosphorescence, first paper), Annalen der Physik, 34: 446-463. From page 447: "Ich möchte für diese zweite Art der Lichterregung, für die uns eine einheitliche Benennung fehlt, den Namen Luminescenz vorschlagen, und Körper, die in dieser Weise leuchten, luminescirende nennen." [For this second type of light excitation, for which we lack a consistent name, I would like to suggest the name of "luminescence", and call "luminescing" [any] bodies that glow in this way.]
- ^ A Brief History of Fluorescence and Phosphorescence before the Emergence of Quantum Theory Bernard Valeur and Mario N. Berberan-Santos J. Chem. Educ., 2011, 88 (6), pp 731–738doi:10.1021/ed100182h
- ^ Piezoluminescence phenomenon N. A. Atari Physics Letters A Volume 90, Issues 1-2, 21 June 1982, Pages 93-96 doi:10.1016/0375-9601(82)90060-3
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