Fluorescence

Substances like minerals, plants, fungi, microbes, and organic and inorganic chemicals, can absorb UV radiation, causing electrons to jump to a higher energy level. When the electrons return to a lower energy level, they emit a portion of the absorbed energy as visible light.

• Fluorescence is used for signs, safety vests, and other applications in which high visibility is important.
• In fluorescent tubes, an electric current is passed through mercury vapour, producing ultraviolet radiation along with a blue light.