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Triboluminescence is an optical phenomenon in which light is generated through the breaking of chemical bonds in a material when it is pulled apart, ripped, scratched, crushed, or rubbed (see tribology). The phenomenon is not fully understood, but appears to be caused by the separation and reunification of electrical charges. The term comes from the Greek τρίβειν ("to rub"; see tribology) and the Latin lumen (light). Triboluminescence can be observed when breaking sugar crystals and peeling adhesive tapes.

Triboluminescence is often used as a synonym for fractoluminescence (a term sometimes used when referring only to light emitted from fractured crystals). Triboluminescence differs from piezoluminescence in that a piezoluminescent material emits light when it is deformed, as opposed to broken. These are examples of mechanoluminescence, which is luminescence resulting from any mechanical action on a solid.



Uncompahgre Ute Indians[edit]


Later descriptions[edit]



Mechanism of action[edit]

Materials scientists have not yet arrived at a full understanding of the effect, but the current theory of triboluminescence — based upon crystallographic, spectroscopic, and other experimental evidence — is that upon fracture of asymmetrical materials, charge is separated. When the charges recombine, the electric discharge ionizes the surrounding air, causing a flash of light. Research further suggests that crystals which display triboluminescence must lack symmetry (thus being anisotropic in order to permit charge separation) and be poor conductors. However, there are substances which break this rule, and which do not possess asymmetry, yet display triboluminescence anyway, such as hexakis(antipyrine)terbium iodide.[5] It is thought that these materials contain impurities, which confer properties of asymmetry to the substance.



Ordinary Pressure-sensitive tape ("Scotch tape") displays a glowing line where the end of the tape is being pulled away from the roll.[7] In 1953, Soviet scientists first observed that unpeeling a roll of tape in a vacuum produced X-rays.[8] The mechanism of X-ray generation was studied further in 2008.[9][10][11]




EMR propagation during fracturing[edit]

The emission of electromagnetic radiation (EMR) during plastic deformation and crack propagation in metals and rocks have been studied. The EMR emissions from metals and alloys have also been explored and confirmed. Molotskii presented a dislocation mechanism for this type of EMR emissions.[16] Recently, Srilakshmi and Misra reported an additional phenomenon of secondary EMR during plastic deformation and crack propagation in uncoated and metal-coated metals and alloys.[citation needed]


EMR during the micro-plastic deformation and crack propagation from several metals and alloys and transient magnetic field generation during necking in ferromagnetic metals were reported by Misra (1973–75), which have been confirmed and explored by several researchers. Tudik and Valuev (1980) were able to measure the EMR frequency during tensile fracture of iron and aluminum in the region 1014¬¬ Hz by using photomultipliers. Srilakshmi and Misra (2005a) also reported an additional phenomenon of secondary electromagnetic radiation in uncoated and metal-coated metals and alloys. If a solid material is subjected to stresses of large amplitudes, which can cause plastic deformation and fracture, emissions such as thermal, acoustic, ions, exo-emissions occur. With the discovery of new materials and advancement in instrumentation to measure effects of EMR, crack formation and fracture; the EMR emissions effect becomes important.

Deformation induced EMR[edit]

The study of deformation is essential for the development of new materials. Deformation in metals depends on temperature, type of stress applied, strain rate, oxidation and corrosion. Deformation induced EMR can be divided into three categories: effects in ionic crystal materials; effects in rocks and granites; and, effects in metals and alloys. EMR emission depends on the orientation of the grains in individual crystals since material properties are different in differing directions.[17] Amplitude of EMR pulse increases as long as the crack continues to grow as new atomic bonds are broken and it leads to EMR. Pulse starts to decay when crack halts.[18] Observations from experiments showed that emitted EMR signals contain mixed frequency components.

Test methods to measure EMR[edit]

Most widely tensile test method is used to characterize the mechanical properties of materials. From any complete tensile test record, one can obtain important informations about the material’s elastic properties, the character and extent of plastic deformation, yield and tensile strengths and toughness. These informations which can be obtained from one test justifies the extensive use of tensile test in engineering materials research. Therefore, investigations of EMR emissions are mainly based on the tensile test of the specimens. From experiments, it can be shown that tensile crack formation excites more intensive EMR than shear cracking, increasing the elasticity, strength and loading rate during uniaxial loading increases amplitude. Poissions ratio is a key parameter for EMR characterization during triaxial compression.[19] If the poissions ratio is lower, it is harder for the material to strain transversally and hence higher is the probability of new fractures. Mechanism of plastic deformation is very important for safe operation of any component under dynamic conditions.

Uses and applications[edit]

This EMR can be utilized in developing sensors/smart materials. This technique can be implemented in powder metallurgy technique also. EMR is one of these emissions which accompany large deformation. If an element can be identified which gives maximum EMR response with minimum mechanical stimulus then it can be incorporated into main material and thus set new trends in the development of smart material. The deformation induced EMR can serve as a strong tool for failure detection and prevention.

See also[edit]


  1. ^ BBC Big Bang on triboluminescence
  3. ^ Bacon, Francis. Novum Organum
  4. ^ See Wikipedia's article: Barometric light.
  5. ^ W. Clegg, G. Bourhill and I. Sage (April 2002). "Hexakis(antipyrine-O)terbium(III) triiodide at 160 K: confirmation of a centrosymmetric structure for a brilliantly triboluminescent complex". Acta Crystallographica Section E 58 (4). Retrieved 21 September 2013. 
  6. ^ "Rockhounding Arkansas: Experiments with Quartz". Retrieved 2012-10-09. 
  7. ^ Nature (journal). Sticky tape generates X-rays
  8. ^ Karasev, V. V.; Krotova, N. A.; Deryagin, B. W. (1953). "Study of electronic emission during the stripping of a layer of high polymer from glass in a vacuum". Doklady Akademii Nauk SSSR (Proceedings of the USSR Academy of Sciences) 88: 777–780. 
  9. ^ Camara, C. G.; Escobar, J. V.; Hird, J. R.; Putterman, S. J. (2008). "Correlation between nanosecond X-ray flashes and stick-slip friction in peeling tape". Nature 455: 1089–1092. doi:10.1038/nature07378. 
  10. ^
  12. ^
  13. ^ "Science News Online - This Week - News Feature - 5/17/97". 1997-05-17. Retrieved 2012-10-09. 
  14. ^ "IUPAC Gold Book - triboluminescence". 2012-08-19. Retrieved 2012-10-09. 
  16. ^ Chauhan, V.S.1 (2008), "Effects of strain rate and elevated temperature on electromagnetic radiation emission during plastic deformation and crack propagation in ASTM B 265 grade 2 titanium sheets", Journal of Materials Science 43: 5634–5643, Bibcode:2008JMatS..43.5634C, doi:10.1007/s10853-008-2590-5 
  17. ^ KUMAR, Rajeev (2006), "Effect of processing parameters on the electromagnetic radiation emission during plastic deformation and crack propagation in copper-zinc alloys", Journal of Zhejiang university science A 7 (1): 1800–1809, doi:10.1631/jzus.2006.a1800 
  18. ^ Frid, V. (2006), "Fracture induced electromagnetic radiation" (PDF), Journal Applied physics 36: 1620–1628 
  19. ^ Frid, V. (2000), "Electromagnetic radiation method water-infusion control in rockburst-prone strata", Journal of Applied Geophysics 43 (1): 5–13, Bibcode:2000JAG....43....5F, doi:10.1016/S0926-9851(99)00029-4 


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