What Is Triboluminescence?

I can say without any doubt that you have used Scotch tape or sticky tape at least once in your life… and probably far more. It’s a nifty little thing, isn’t it? It helps you stick stuff together, seal a crack or mend a tear in a page. It’s a very useful component of the average stationery kit.

Scotch tape

Scotch tape.(Photo Credit : Flickr)

However, did you know that doing something as prosaic as peeling scotch tape can actually release radiation in a vacuum? Oddly enough, it’s true, due to a process called Triboluminescence.


Triboluminescence is an optical phenomenon that involves the emission of light as a result of breaking chemical bonds when a material is scratched, rubbed, crushed or pulled apart in its solid state. The materials that emit light when acted upon in this manner are called triboluminescent materials.

Interestingly, the exact light emission mechanism of such materials is still unknown to us, but we know that this phenomenon is the result of an electric discharge. Some examples of triboluminescent materials include sucrose, coumarin, quartz, resorcinol etc. Even diamond may begin to glow when it’s rubbed.

Diamond piece

When diamonds are sawed, they often glow due to triboluminescence. (Photo Credit : Pixabay)

Now that you have a bit of background about triboluminescence, let’s talk about scotch tape and X-rays.

Scotch tape X-ray

Apparently, when you peel scotch tape in a vacuum, it releases X-rays. This experiment has actually been performed by researchers at the University of California, Los Angeles. They took an ordinary piece of sticky tape and peeled it in a vacuum. The action generated X-rays, and a high enough ‘quantity’ was produced to actually take the image of one of the scientists’ fingers.

Juan Escobar, one of the members of the research team, remarked, “At some point, we were a little bit scared!” Fortunately, he and other members of the team soon realized that this optical phenomenon occurs only when a kit containing sticky tapes is used in a vacuum setting.

Scotch tape X ray

X-rays are emitted as the tape is peeled.

Why does peeling Scotch tape in vacuum produce X rays?

When a crystal is scratched or crushed, opposite charges are separated. When these charges are neutralized, they release energy in the form of light.

Basically, peeling a strip of adhesive from a smooth surface is a ‘violent’ process of sorts. As the adhesive stretches into strands or fibrils that suddenly snap apart, at the tape-surface juncture, electrical activity is generated. This is what leads to the faint glow as the tape is peeled off in vacuum (within a dark room).

When you peel tape, the adhesive and the ‘tape-back’ sides become charged with opposite polarities, although this is the part that is not perfectly understood by scientists quite yet. When these opposite charges combine, electric discharge ionizes the surrounding air, which causes a flash of light!

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About the Author

Ashish is a Science graduate (Bachelor of Science) from Punjabi University (India). He spends a lot of time watching movies, and an awful lot more time discussing them. He likes Harry Potter and the Avengers, and obsesses over how thoroughly Science dictates every aspect of life… in this universe, at least.

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