Honor Chemistry, Per 7
December 21, 2010
Since glow sticks have been invented, consumers have wondered how scientists are able to create these magical sticks of light. They work without producing heat. They don’t need a battery or a bulb, Magic? This “cool” light is called luminescence. Unlike incandescence, which is light from heat energy, luminescence can be emitted at normal or lower temperatures. There are several types of luminescence, bioluminescence, is what happens in fireflies: as the “bio” prefix indicates, it’s caused by a chemical reaction in living things, cathodoluminescence, is caused by electron beams. And Chemiluminescence. Chemilumiescence is the magic behind the glow stick. Chemiluminescence is what happens in glow sticks. The energy that is needed is supplied by chemical reactions. The chemical reaction of chemiluminescence releases energy that is absorbed by electrons in molecules. Electrons in the atoms make a quantum leap once they absorb the energy from the reaction. The electrons must either jump to or fall back from one quantum level to another quantum level this is the quantum leap. (1) The electron jumps to a higher level; at this point the electron is in what is called the excited state, or a higher quantum. As the electron returns to the lower state, it releases the energy as a photon of light; the photon is the light that we see. To make this easier to understand, think of a rock being picked up. When a person picks up a heavy rock, it takes energy, just as it takes energy for an electron to jump to a higher energy level. When the person drops the rock and it falls to the ground, the energy is released as sound energy. And in the case of the electron, the energy that is released is light energy instead of sound energy. Planck’s equation, E = hv was created by Max Planck and Albert Einstein. The equation relates the energy of a Quantum leap “E” to the frequency, or color of the light that is given off “v”. Chemists have been fascinated with “cold light” for as long as there have been fireflies flying around the night skies. In the first steps to making their very own “cold light,” they knew what was required: a molecule that radiates light when it is excited and an energy source to excite that molecule. In the early 1960s, a young chemist by the name of Edwin A. Chandross was looking for a way to describe chemiluminescence. Chandross knew that peroxides had a large amount of potential energy. He concluded that they were likely to be participants in the future of chemiluminescence. In his work, Chandross was able to produce a reaction that produced a “cold light”. However, it wasn’t very efficient. Although Chandross’s work wasn’t efficient, it was a major step in the right direction for chemiluminescence. Edwin A. Chandross didn’t realize that his discovery had great potential. Sadly he never patented it. Around the same time, another chemist by the name of Michael M. Rauhut began studying some of Chandross’s work. Rauhut and his team began searching for a reaction that would be powerful enough to be practical to use. Eventually they designed a phenyl oxalate ester that, when mixed with hydrogen peroxide and a fluorescent dye, produced a reaction not quite as efficient as a firefly. The group called it Cyalume, which became its name when Rauhut’s company, American Cyanamid, began selling it as one of their chemical light products. The basic structure of a glow stick is particularly simple. It contains the somewhat bendable plastic outer shell and the easily broken inner glass vial. When the glow stick is ready to be used, an individual will grip each end of the glow stick and bend it. As the flexible external plastic casing of the glow stick begins to bow, it comes in contact with the internal glass vial, and begins to apply pressure to it. Because the inner glass vial is less flexible...
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