<unk>  (sometimes "chemoluminescence") is the emission of
light (luminescence) with limited emission of heat as the result of a chemical reaction. Given reactants A and B, with an excited intermediate ◊, we have:
For example, if  [A] is luminol and [B] is hydrogen peroxide in the presence of a suitable catalyst we have:
where:
where 3-APA is 3-aminophthalate
3-APA[◊] is the excited state fluorescing as it decays to a lower energy level.
The decay of the excited state[◊] to a lower energy level is responsible for the emission of light. In theory, one photon of light should be given off for each molecule of reactant, or Avogadro's number of photons per mole. In actual practice, non-enzymatic reactions seldom exceed 1% QC, quantum efficiency.
A standard example of<unk>  in the laboratory setting is found in the luminol test, where evidence of blood is taken when the sample glows upon contact with iron. When<unk>  takes place in living organisms, the phenomenon is called bioluminescence. A lightstick emits light by<unk> .
Chemiluminescence
Fluorescence
Absorption spectrum
Spectroscopy
Visible spectrum
Image analysis
Hounsfield scale
Extraction ratio