luminescensen

Luminescence is the emission of light by a substance not resulting from heat. This phenomenon is distinct from incandescence, which is light produced by high temperatures. Luminescence occurs when a material absorbs energy from an external source and then re-emits that energy as photons of light. The specific wavelength, and therefore color, of the emitted light depends on the material's composition and the energy input.

There are several types of luminescence, classified by the source of energy. Photoluminescence occurs when a substance absorbs light and then re-emits light. This is further divided into fluorescence, where the emission is nearly instantaneous, and phosphorescence, where the emission is delayed. Chemiluminescence is light produced by a chemical reaction, such as the glow sticks used in celebrations. Bioluminescence is a form of chemiluminescence that occurs in living organisms, like fireflies or deep-sea creatures. Triboluminescence is light generated by friction or fracture of a solid material, often observed when crushing sugar crystals in the dark. Electroluminescence is the emission of light in response to an electric current or field, the principle behind LEDs.

Luminescence has numerous practical applications. It is used in fluorescent lighting, LED displays, security markings, medical imaging, and scientific research. The study of luminescence helps us understand the properties of materials and their interactions with energy.