concept

Chemiluminescence

Light produced directly by a chemical reaction, with no heating step. A suitable reaction kicks its product into an excited electronic state; as the product drops back to its ground state, the energy difference leaves as a particle of light. Unlike incandescence (a filament or a flame), chemiluminescence wastes almost no heat - which is why it is called "cold light". Bioluminescence is chemiluminescence performed inside a living organism.