|How does luminol work? — CW, San Antonio, TX
Luminol produces light during a chemical reaction with either molecular oxygen or a mixture of potassium ferricyanide and hydrogen peroxide and is probably the basis for most light sticks. In an alkaline (basic) solution, the luminol molecule becomes a dianion, a molecule with two negative charges on it. In this dianion form, the molecule has two nitrogen atoms exposed to the solution and these nitrogen atoms are easily replaced by two oxygen atoms. When that exchange takes place, a molecule of nitrogen gas is released and the final oxidized luminol is left in an electronically excited state. This molecule quickly gets rid of its excess energy by emitting light.