Luminescence
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 by chemical 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]
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
- Bioluminescence, emission by a living organism
- Chemiluminescence, a result of a chemical reaction
- Crystalloluminescence, produced during crystallization
- Electroluminescence, a result of an electric current passed through a substance
- 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[2]
- Photoluminescence, a result of absorption of photons
- Fluorescence, photoluminescence in which the emitted photons are of lower energy than those absorbed
- Phosphorescence, fluorescence slightly delayed after initial absorption of radiation (on a scale of seconds 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
References
- ^ A Brief History of Fluorescence and Phosphorescence before the Emergence of Quantum Theory Bernard Valeur and Mrio N. Berberan-Santos J. Chem. Educ., 2011, 88 (6), pp 731–738 doi: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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