Luminescence

Luminescence, nonthermal (heatless) emission (particularly light) caused by electron movement from more energetic states to less energetic states. Including fluorescence and phosphorescence, types of luminescence are named for the mode of excitation. In chemiluminescence the energy source is a chemical reaction, while bioluminescence occurs in biochemical reactions.

See also: Bioluminescence; Fluorescence; Phosphorescence.