![]() In our experiment the wintergreen in the mint absorbs a lot of UV energy that we can't see, and emits greenish-blue light which we can see, so it appears much brighter to us. Fluorescent molecules can absorb energy of short wavelengths and emit their own light at a longer wavelength. This is because wintergreen, the flavoring used in these mints, is a natural fluorescent dye called methyl salicylate. You should have noticed that the flash of light from the Wint-O-Green Life Saver was significantly brighter, and may have also seemed to last a little longer. Most of the light energy is emitted in the ultraviolet (UV) part of the electromagnetic spectrum, which is just outside the range of light that is visible to humans, but fortunately there is a bit of violet and blue light that we can see. These plasma ions can then slam into other molecules and transfer energy which causes them to emit photons of light. Since electrons have a negative electrical charge and the protons in the nucleus have a positive charge, separating these charges can create an electrical field strong enough to rip electrons off gas molecules in the air, a process called ionization, and creates a localized plasma. Many materials, like the sugar in this experiment, have a very special crystalline structure that causes electrons to be ripped away from the nucleus of their atoms. Triboluminescence is not very well understood by scientists, but most think it is similar to the lightning you see during storms or during one of our cool electricity demonstrations, which is actually a type of plasma discharge. And though it does look sort of like the sparks you see when some metals (like iron) are scratched or scraped by very hard materials (like flint), those are actually produced by spontaneous combustion (burning) of the metal as freshly cut surfaces of very small pieces react with oxygen from the air. It's also not a chemical reaction like the light-sticks you may have played with before. Nothing is burning, glowing or getting hot like the filament in a light bulb (although there may be a little heat from the friction as the candy is crushed). This is a demonstration of tribo-luminescence, which means to make light by rubbing, scratching or crushing something, which is very different from most of the ways you are familiar with to make light. What's Happening: This is not a magic trick or an optical illusion- you really did produce light from an ordinary piece of candy!. What color is the light? Does it last very long? Does the candy get hot? Cold? If you have different types of candy or some sugar cubes, do you observe any differences in the light from each? If you have a sugar-free mint, does it make a flash of light too? If you have any other candies, try those and make observations. If it doesn't work at first, try again, and make sure the room is dark and your eyes are adjusted. ![]() Observations: Does the candy glow in the dark before you crush it? Did you observe a flash of light as you crunched the candy with your pliers? It's not very bright, and it happens very quickly, but you should see a cool flash of light, almost like a spark.
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