Light Sticks
Adam’s Peak Pilgrimage, Sri Lanka: Pilgrims of all religions flock to climb the steps on this steep mountain path, which is illuminated with light. Light sticks, portable chemiluminescent devices, are one way to introduce light in dark places.
Credit: iStock
In the early 1960s, when scientists took the first steps toward developing their own version of a firefly, they knew what was required: a molecule that radiates light when it’s excited and an energy source to excite the molecule. There are numerous possible energy sources, such as light, heat, and electricity. In chemiluminescence, that source is a chemical reaction.
But the reaction has to generate a huge bundle of available energy, and transfer it as a package instantaneously to the fluorescent molecule without radiating any as heat. Known examples of such perfectly orchestrated reactions were few.
Also in the early 1960s, Edwin A. Chandross, a young chemist at Bell Labs in Murray Hill, N.J., was searching for a general way to explain chemiluminescence. Peroxides, with their potential to liberate large amounts of energy during some chemical reactions, seemed to be likely participants.
After a number of experiments, he found to his great excitement that oxalyl chloride mixed with hydrogen peroxide and a fluorescent dye produced chemical light. The efficiency was only about 0.1\, but it was the foundation from which sprang modern chemiluminescence.
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Excerpted with permission, Chemical & Engineering News
Copyright © 1999 American Chemical Society