==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 **Candoluminescence, is light emitted by certain certain materials at elevated temperatures, which differs from the blackbody 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, 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, 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) **Raman emission, photoluminescence as a result of inelastic light scattering, (lifetime: nanoseconds) *Radioluminescence, 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) ==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 Luminescence occurs in some minerals when they are exposed to low-powered sources of ultraviolet or infrared electromagnetic radiation (for example, portable UV lamps), at atmospheric pressure and atmospheric temperatures.
Diagram above: In silicate minerals, when radiation interacts with the crystal (Irradiation), energy pushes an electron into the conduction band and leaves a ‘hole’ in the valence band.
The electron may become trapped at a defect site (T1, T2 etc) for some time (Storage).
It can be caused by chemical reactions, electrical energy, subatomic motions, or stress on a crystal, which all are ultimately caused by Spontaneous emission.
This distinguishes luminescence from incandescence, which is light emitted by a substance as a result of heating.
The guidelines will help archaeologists and site investigators to assess whether luminescence dating will be of value in providing chronological information for understanding their site.
Luminescence is emission of light by a substance not resulting from heat; it is thus a form of cold-body radiation.
(Modified from Aitken, 1990; Duller, 2008) Through controlled experiments the emission of luminescence can be controlled and measured and then used to estimate the equivalent dose (De).
The dose rate (Dr) is the amount of energy absorbed per year from radiation in the environment surrounding the sample material and is estimated by measuring the amount of radioactivity directly or by chemically analyzing the surrounding material and calculating the concentration of radioisotopes. Luminescence Dating: Guidelines in Using Luminescence Dating in Archaeology.
This property of these minerals can be used during the process of mineral identification at rock outcrops in the field, or in the laboratory.
==References== ==External links== *[ database of luminescent dyes] Category: Light sources Category:19th-century neologisms Texte soumis à la licence CC-BY-SA.
The age range for pottery and other ceramics covers the entire period in which these materials have been produced.