DO try this at home: Triboluminescence

By: Nicole Darman 06/17/2015 1:19PM
Category: Everyday Physics

Credit: Carlos Camara, Juan Escobar and Seth Putterman

Finally! An experiment you can do at home without fancy equipment - and years of training. Triboluminescence is the act of making light by rubbing, scratching or crushing specific materials. Observing triboluminescence is not only safe for all ages, but also provides a beautiful sight to behold. Better still, you can create this natural phenomenon using basic household items!

What Is Triboluminescence?

Triboluminescence is when the breaking of chemical bonds in a material generates visible light. This is achieved by scratching, crushing, rubbing, ripping and pulling apart materials. In particular, this event can be seen in fractured crystals such as sugar and also in the disjoint of adhesive tape as it is peeled off the roll.

The term “tribo” comes from the word tribology, which is the study of interactive surfaces in relative motion, including principles such as friction, lubrication and wear.

Unlike common methods of producing light, triboluminescence does not involve burning, glowing, heating or any chemical reactions. It also differs from the sorts of sparks you would see from particular metals when they are scratched by other hard metals. Those sparks are from very small pieces of freshly cut metal surface reacting with the oxygen in the air, also known as spontaneous combustion.

Why Does Triboluminescence Occur?

So if it isn’t caused by burning things or chemical reactions, then what is actually happening? Although it isn’t well understood by scientists, it is believed that triboluminescence is similar to lightning during storms, whereby energy is transferred when electrons are removed from atoms and interact with the surrounding matter.

It all begins with the special crystalline structure that certain materials possesses. Materials capable of triboluminescence are described as asymmetric - this means that the positive and negative charges of the particles that make up the material are able to be separated (i.e. the electron and the nucleus). When this structure is disturbed, it causes the electrons (negative charge) to be separated from the nucleus of the atoms (positive charge). The free electrons briefly interact with the molecules in the air, causing electric discharge (when an electric current flows through a medium like air caused by the interaction between electrons and air molecules) to occur. This results in a transfer of energy, often in the form of light, which is what we see.

Unfortunately, most of the light emitted is out of the visible spectrum (ultraviolet, or UV). But, depending on the material, is can visible as violet, blue and sometimes even green light. For example, the Wint-O-Green Life Saver contains a natural fluorescent dye that is able to absorb energy at shorter wavelengths (UV, violet, blue) and emit light at longer wavelengths (green, yellow, red). This allows us to view the light in the visible spectrum range, and with a greater intensity. By simply placing the Life Saver in your mouth and crunching down with your teeth, you should be able to see the glow!

Uses And Applications

Not only is this phenomenon fun to look at, but it has some practical applications too. Scientists can utilize the light emitted from the fractured material to:

Since there is an abundance of materials that exhibit triboluminescence (all with a variety of characteristics), scientists can perform tests to find the most efficient material for their product.

Since there is an abundance of materials that exhibit triboluminescence (all with a variety of characteristics), scientists can perform tests to find the most efficient material for their product.

Can I Do It At Home?

Of course! We would actually be disappointed if you didn’t try it.

Here is a list of common household items that exhibit triboluminescence:

  • Wint-O-Green flavored Life Savers (crush in a bag with pliers)
  • Regular candy (crush in a bag with pliers)
  • Sugar cubes or regular sugar (rub them together or use a mortar and pestle)
  • Pieces of quartz or rose quartz (rub them together or use a steel pin)
  • Chewing candy in your mouth (a bit harder to see)
  • Some adhesive tapes (peeling off the roll or unpeeling a piece that is stuck together)

Along with these materials, you will need an extremely dark room. This works best if you do it at night in a dark room. Make sure you give your eyes a few minutes to adjust to the darkness before smashing away at your material. If you need to use a light, try using a red light as it is the least invasive color when it comes to night vision (astronomers often do this when observing).

Here at Fiat Physica we attempted the triboluminescence challenge using regular sugar and packing tape. Unfortunately we didn’t see any pretty blue light from the sugar, which may be due to the mortar and pestle blocking the view. However, we DID see it in the packing tape! We couldn’t quite capture it on camera, but we recommend trying that material for instant satisfaction.

Think you have what it takes? Send in your attempt at producing triboluminescence by tagging #MakePhysicsHappen on Instagram, Twitter, or Facebook, and we'll feature our favorites!

Further instructions can be found here.

Love science? Get involved at the ground floor of discovery and help make physics happen. Click here to explore science in the making.

Posted on: 06/17/15 1:19PM
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Nicole Darman
Blog Contributor
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Physics graduate working in maths education and dabbling in science writing.

#MakePhysicsHappen @fiatphysica

“Fiat Physica shall hand the steering wheel of scientific innovation to the public, allowing them to contribute to science, communication, and discovery directly.”

Szabolcs Marka

Chair of the Education and Public Outreach Committee, LIGO and Associate Professor of Physics, Columbia University
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