Bioluminescent reactions use (adenosine triphosphate) as a source of energy. The structure of the light-producing molecules varies from species to species, but they are all given the generic name luciferin. The structure of firefly luciferin is shown in , left. When fireflies glow, the luciferin is oxidised to produce an excited complex, which falls back down to the ground state, releasing a photon of light, just like the chemiluminescent reaction of luminol described in . However, fireflies do not use hydrogen peroxide and potassium hexacyanoferrate(III) to oxidise luciferin; instead they use molecular oxygen and an enzyme called luciferase (this is also a generic name – luciferases vary from species to species).
The mechanism for this reaction is outlined extensively throughout this site but the key difference to note is that no radiation is absorbed – the energy required to emit light comes from the energetics of the chemical reaction. The emission could proceed either from a (fluorescence) or (phosphorescence) state. "Light Sticks" are a popular example of Chemiluminescence.
Mechanism of cobalt catalysis of luminol …
When you snap a glow stick and it begins to glow, the light produced is an example of chemiluminescence (see ). Glow sticks comprise a plastic tube containing a mixture including diphenyl oxalate and a dye (which gives the glow stick its colour). Inside the plastic tube is a smaller glass tube containing hydrogen peroxide. When the outer plastic tube is bent, the inner glass tube snaps, releasing the hydrogen peroxide and starting a chemical reaction that produces light (see ). The colour of light that a glow stick produces is determined by the dye used (see ).
Biology, Chemistry and Earth Homework
162-165 (2012).The chemiluminescence (CL) emission spectra of luminol were recordedusing Fuss spectrograph in different aqueous aliphatic amines usingsodium persulphate alone and mixture with hydrogen peroxide as anoxidant.
It begins from 3-nitrophthalic acid
Glowing jellyfish, flickering fireflies, fun glow sticks; Emma Welsh introduces the beautiful and mysterious world of chemiluminescence.
Chemiluminescence - the oxidation of luminol | …
Forensic scientists use the reaction of luminol to detect blood at crime scenes. A mixture of luminol in a dilute solution of hydrogen peroxide is sprayed onto the area where the forensic scientists suspect that there is blood. The iron present in the haem unit of haemoglobin (see ) in the blood acts as a in the reaction described in . The room must be dark and if blood is present, a blue glow, lasting for about 30 seconds, will be observed. The forensic investigators can record this glow by using photographic film, which can be used as evidence in court for the presence of blood at the scene. (For a teaching activity about forensic science, see .
Chemiluminescence - the oxidation of luminol
In the demonstration below, the light blue luminol solution and the colorlesshydrogen peroxide solution are poured together in a funnel, to which a coil ofclear tubing has been attached.