Types of Luminescence
Luminescence manifests itself in various forms, each defined by distinct mechanisms and characteristics. The key types of luminescence include fluorescence, bioluminescence, chemiluminescence, phosphorescence, crystalloluminescence, photoluminescence, electroluminescence, mechanoluminescence, radioluminescence, and thermoluminescence.
Chemiluminescence involves the emission of light resulting from a chemical reaction. This phenomenon is observable by bending and shaking a light stick containing an encapsulated chemical solution, initiating a reaction when mixed. An example is bioluminescence, where living organisms, such as the jellyfish aequorea victoria, produce light through the reaction of luciferin with oxygen catalyzed by the enzyme luciferase.
Phosphorescence denotes a material’s ability to absorb energy from a light source (e.g., flashlight) and emit light even after the source is removed. Objects exhibiting a glow in the dark effect absorb and store energy from a flashlight, re-emitting it as light when the flashlight is turned off.
Fluorescence is the emission of light by a material when exposed to light. Unlike phosphorescence, fluorescence ceases once the light source is removed. Materials exhibiting fluorescence emit light only while exposed to the radiation source.
Crystalloluminescence occurs during crystallization, with light suggested to emanate from small cracks in the crystal. For instance, the crystallization of potassium iodide and KCL exhibits luminescence in specific regions.
Electroluminescence involves the production of light due to the passage of an electric current or an electric field. Examples include cathodoluminescence, occurring when electrons collide with a luminescent material. Electroluminescence uniquely converts electric energy directly into visible light.
Radioluminescence entails the generation of optical photons through the interaction of ionizing radiation with matter. Tritium-excited luminous paints on watch dials exemplify this phenomenon.
Thermoluminescence refers to the emission of light from certain minerals and crystalline materials upon heating. Quartz or calcite, having previously absorbed energy, re-emit light in this process.
Photoluminescence involves a molecule absorbing a photon in the visible region, exciting an electron, and subsequently radiating a photon as the electron returns to its ground state. Examples include fluorescence and phosphorescence, distinguished by the rapidity of photon emission.
Bioluminescence is the production and emission of light by a living organism. Bioluminescent creatures are found throughout marine habitats, from the ocean surface to the deep seafloor.
Mechanoluminescence is light emission resulting from any mechanical action on a solid. It can be produced through ultrasound, or through other means.
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