Chemiluminescence
by: Gagandeep Dhaliwal
A glow stick is a sheer plastic tube that produces a brilliant light. A glowstick is also known as glow tube or light stick or glow light stick.
A glow stick is typically a plastic cylindrical rod about four or five inches (10 to 13 cm) long and less than an inch (2.5 cm) in diameter. The transparent stick contains two chemical fluids in two different compartments. The outer compartment of the tube carries one chemical fluid and the inner compartment carries the other. The inner compartment is brittle either made of glass or brittle plastic.
The inner brittle part breaks on bending the glowstick and helps inter mingling the two chemical fluids. A fierce chemical reaction takes place emitting bright light but not necessarily heat.
The glowsticks are used in the military, recreational driving at night, marching bands at night, entertainment parties, raves, concerts, dance clubs, Halloween eves etc. The glowsticking is the use of glowsticks in dance.
Chemistry:
The phenomenon of the chemical reaction in the glow sticks is known as “chemiluminescence”. The chemicals used to create the reaction in glow sticks are usually hydrogen peroxide and a mixture of phenyl oxalate ester and the fluorescent dye. The fluorescent dye gives the glow stick its color.
The outer compartment of the tube contains a mixture of the dye and a derivate of phenyl oxalate ester (cyalume) and the inner brittle part contains concentrated hydrogen peroxide.
A ferocious reaction takes place on mixing the peroxide with the phenyl oxalate ester. The ester is oxidized, giving out 2 molecules of phenol and 1 molecule of peroxyacid ester. The peroxyacid decomposes spontaneously to carbon dioxide, releasing energy that excites the dye that then de-excites by releasing a photon. The wavelength of the photon depends on the structure of the dye.
Different dyes can be used to produce different color lights. The 9,10-bis (phenylethynyl) anthracene gives green light, 9,10-diphenylanthracene emits blue light, 5,6,11,12-tetraphenylnaphthacene emit red light. The glowsticks dyes usually emit fluorescent light when exposed to ultraviolet radiation. Therefore even a spent glowstick shines under a black light.
The other chemicals used in glow sticks may include sodium salicylate as a catalyst, bis (2-ethylhexyl) phthalate (DCHP) as a solvent, bis (phenyl) oxalate, bis (2,4,5-trichlorophenyl-6-carbopentoxyphenyl) oxalate (CPPO).
The chemical reaction gets accelerated on heating a glow stick and the glowstick glows brighter, but for a shorter span. The cooling on the contrary decelerates the reaction that helps a sick glow longer, but dimmer.
About The Author
Gagandeep Dhaliwal owns the website http://www.glow-sticks.org/, a comprehensive guide on glow sticks, offering volumes of info and tips on buying glow stick, cheap glow stick, rave glow stick, giant glow sticks, military glow sticks etc. For more info on glowsticks, visit, http://www.glow-sticks.org/subcat/Glow-Sticks/.
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