Luminescence

Luminol and haemoglobin, an example of chemiluminescence

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][2]

UV-photoluminescence in the microbiological diagnostics

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 chemical reaction
  • Bioluminescence, a result of biochemical reactions in a living organism
  • Electrochemiluminescence, a result of an electrochemical reaction
  • Lyoluminescence, a result of dissolving a solid (usually heavily irradiated) in a liquid solvent
• 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, 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]
  • Sonoluminescence, a result of imploding bubbles in a liquid when excited by sound
• 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
• Thermoluminescence, the re-emission of absorbed energy when a substance is heated^[4]
  • Cryoluminescence, the emission of light when an object is cooled (an example of this is wulfenite)

Applications

• Light-emitting diodes (LEDs) emit light via electro-luminescence
• Phosphors, materials that emit light when irradiated by higher-energy electromagnetic radiation or particle radiation
• Phosphor thermometry, measuring temperature using phosphorescence
• Thermoluminescence dating
• Thermoluminescent dosimeter

References

1. 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.]
2. 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 731–738 doi:10.1021/ed100182h
3. 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
4. Meetei, Sanoujam Dhiren. "Synthesis, Characterization and Photoluminescence of ZrO2:Eu3+ Nanocrystals" (PDF). Retrieved 18 December 2014.

External links

• Fluorophores.org A database of luminescent dyes