Welcome to my homepage - Wolfgang Stadlbauer








Experiments with charme

CHEMILUMINESCENCE ("Cold light")

Deutsche Version


Chemiluminscence experiments are part of the "Chemical laboratory for students of biology"
Moreover it is an experiment favored by pupils.

Chemiluminescence is the reversed case of a photo reaction: by a chemical reaction, an excited particle is formed, which looses its energy by producing a light quantum of light. The most important characteristic is that the light is be emitted in the cold (e.g. different from the temperature light of gases. Chemiluminescence es discovered already from the ancient alchimists, who found the slow oxidation of yellow/white phosphorus. Generally, chemiluminescence occurs when the product of an exothermic reaction is formed in the excited state.

There are known a number of reactions of organic compounds, which are emitting visible cold light in a quantity enough for fine experiments. Among these reactions are the oxidation of Lucigenin (a bisacridinium salt) or from Luminol (3-aminophthalic acid hydrazide).

Lucigenin Luminol Luciferin from the firefly
Also the nature has developed some light emitting rections (Bioluminescence) : One of the best known phenomena is the oxidation of Luciferins from the firefly.

LUMINOL

With a solution of luminol in dimethyl sulfoxide, the formation of the light of bioluminescence can be simulated, which can be observed by stimulation of dinoflagellates in the sea by the action of oxygen caused by ships. A practical use could be found for emergency lights (in household, in the mountains, on sea and for diving), detection of oxygen on dangerous places, or in microbiological experiments (showing an anaerobic environment).
The description of an experiment with Luminol can be found here

.

LUCIGENIN

Lucigenin, a Dimethyl-diacridiniumsalt, shows in alkaline peroxide solution a strong luminescence. Both, lucigenin and its oxidation product, N-methylacridone, are strongly fluorescent compounds, which allows to observe the light emission without any energy acceptor.
The most reasonable mechanism (involving a intermediate peroxide) is shown in the reaction scheme - (see description of the experiment with lucigenin) . In the first phase, the color of the fluorescent lucigenin (light green) is emitted, then the color changes to a light blue fluorescence of N-methylacridone.