Autofluorescence

Part of speech: noun

Definitions

1. A process by which materials emit their own light when exposed to certain wavelengths of excitation without requiring added fluorescent dyes
2. The ability of various substances to automatically produce visible light in response to specific excitation wavelengths without the use of external agents
3. The natural phenomenon where a material emits light by itself after being exposed to specific light wavelengths

Etymology: Autofluorescence is a compound of the Greek "autos," meaning "self," which gave English the prefix "auto-," and the older word "fluorescence." The second part is named after a mineral. The mineral fluorite takes its name from Latin "fluor," meaning "flow," a reference to its use as a flux that helped metals melt and run during smelting. Fluorite's name ends in "-ite," a suffix from Latin "-ītis" (ultimately Greek "-ītēs") used for mineral names. Its older English name was "fluorspar," where "spar" came into English from Middle Low German and was used for crystalline minerals that split cleanly. The ending "-escence" comes from Latin "-escere," a suffix meaning "beginning to" or "becoming," so fluorescence describes a process that starts when light hits the material. Autofluorescence, then, is glowing that a substance produces on its own, without any added dye.