A blue line in the dark, it's torn tape glowing
A blue line in the dark, it's torn tape glowing
The friction around you glows (however, I haven't observed _ (: friction "∠) _)

it's a common scene when you pull open the scotch tape to pack the box. However, if you look at it in the dark, sometimes just tearing off the tape can produce an unusual scientific phenomenon: it emits a blue light.

(patience, obvious glow at about 16 seconds and 23 seconds)

so why does the tape glow? The mechanism behind this is not entirely clear, but what is certain is that light is produced when the charge ionizes the surrounding air (similar to lightning). To prove this, you can change the gas environment in which the tape is torn. If it is changed to emit light in a neon environment, it will turn orange-red, indicating that the luminous color really depends on the nature of the gas.

(light emitted by tearing the tape in the neon environment)

when the tape is torn off at a faster speed, the charge transfer and accumulation will occur on the tape, and the accumulated charge is enough to ionize the air and emit light. However, exactly how the charge change occurs is controversial. This phenomenon is called triboluminescence (Triboluminescence). Another everyday object with frictional luminescence is sucrose crystals. Details can be seen in → Today I Learned: in the dark, you can see how rock sugar glows

blue luminescence can be observed in ordinary air environment, and even higher-energy photons appear under special conditions. In one study, when the tape was torn at a speed of 3 cm/s in a moderate vacuum, the researchers observed the production of x-rays. In this process, the X-ray is not continuously emitted, but appears briefly, each time lasting only nanosecond. The researchers were even able to take an x-ray of their fingers with the accumulated x-rays (pictured below). However, the conditions needed to produce x-rays are very special, and you don't need to worry about radiation when you tear the tape.

(photo source: Carlos G. Camara, Juan V. Escobar, Jonathan R. Hird & Seth J. Putterman)

in English materials, this phenomenon is mainly recorded by two types of tape, one is Sikao tape (Scotch tape), the other is waterproof tape (duct tape). But both statements are a little vague: the former is a brand with N different tape products, and the latter does not specify which brand.

the most detailed information I can find on the Internet about which kind of tape is easy to succeed is a paper, in which the following experimental results are summarized for reference:

luminous intensity: Scotch Magic 810 ScotchTransparent 310 Transparent 600 Scotch Tartan 5142 Scotch SuperClear 3120 Olympic cloth tapes.

A little less luminous: ScotchDouble-sided 665 Scotch Tear-by-hand,Scotch Storage 3650 Scotch Strapping 8957 Scotch 310 Brown,OfficeWorks Invisible tapes.

hardly glows: ScotchRemovable 811

if you are interested, you can try more kinds of tape patiently. I have tried the transparent tape on my desk so far, but I haven't succeeded _ (: tape)) _ have time to keep trying.


report that pulling tape produces x-rays: https://www.nature.com/articles/nature07378

tested the luminous effect of various tapes: http://ro.uow.edu.au/cgi/viewcontent.cgi?article=1379&context=aiimpapers

other similar luminous phenomena: cold knowledge: high-speed water flow will glow!

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