X-Ray Emission and Triboluminescence From Unwinding

Scotch Tape

Kyle Peterson, Jake Yeager, and Kristian MadsenX-Ray Image.4

PHYs 43Spring 2009

Triboluminescence

• Triboluminescence is a phenomenon in which light is generate from a crystalline material being broken scratched, crushed, or rubbed.1

1. http://en.wikipedia.org/wiki/Triboluminescence

Triboluminescence

It has been observed that unrolling scotch tape can produce visible light. This emission of light is considered to be triboluminescence. The phenomenon has been observed under different circumstances for hundreds of years, primarily due to crushing crystals in dim light.1

2. Carlos G. Camara, Juan V. Escobar, Jonathan R. Hird & Seth J. Putterman , “Correlation between nanosecond X-ray flashes and stick–slip friction in peeling tape.” Nature 455 (2008): 1089 – 1092.

Triboluminescent light emission.2

Theory

The theory behind this emission of light, is depicted in the image to the right. As the tape is separated, localized regions of charge are created. Electrons travel from the negative regions on one strip to positive regions on the adjacent strip of tape. As they travel some collide with gas molecules. These collisions are of high enough energy to produce photons of light.3

3. http://skullsinthestars.com/2008/11/20/x-rays-from-scotch-tape/

X-Ray Emission

• It has been known for hundreds of years, that the phenomenon of triboluminescence exists, but it wasn’t until more recently that Russian scientists found a broader spectrum of emissions from the same source of excitation.4

4. Kenneth Chang, “Scotch Tape Unleashes X-Ray Power.” The New York Times October 23, 2008.

TheoryThe emission of X-Rays is believed to be caused when the electrons are allowed to travel without collision to the other piece of tape. In approaching the other side they are slowed by atomic interactions and emit braking-radiation in the form of an X-Ray photon. This is known as the bremsstrahlung effect which says that the reduced energy of an electron is emitted as a photon.5

5. Thornton & Rex, Modern Physics: For Scientists and Engineers. Third edition, 2006. Thompson Learning Inc. Page 111-112.

Ef=Ei - hf

Application• UCLA researchers and authors of the publication, “Correlation

between nanosecond X-ray flashes and stick–slip friction in peeling tape”2 believe that this emission method makes X-Ray production possible almost anywhere. Typical devices require very high voltage to produce a worthwhile flux, while they propose the use of only a 9 volt battery in their system.6

6. “Fracture-Driven Portable X-Ray-Electron-Ion Generator (FRAXGEN).” http://www.research.ucla.edu/tech/ucla08-485.htm

7. http://www.daylife.com/photo/04lS48wb0xbKh

Radiograph image of finger.7

UCLA Scientists8

Mythbusters Movie!

AcknowledgementsSpecial Thanks goes to Brad Girod for apparatus

design, parts and consultation,And to Dr. Xuan Ho of SRJC Radiology for use of

facilities and feedback.