Fractured, light emission

The term triboluminescence is often used to describe any light emission occurring upon impact with or grinding of a crystalline material, and is certainly more than one phenomenon (3). Light emissions caused by heating during fracture, such as thermoluminescence and blackbody radiation, are common, but neither they nor chemical reactions such as oxidation are strictly considered triboluminescence they will not be discussed in this paper. 

Triboluminescence (TL) is the phenomenon of light emission during the application of a mechanical stress or by fracture of crystals in a solid sample. The materials presenting this behavior are promising for application in real-time structural damage sensors . 

Triboluminescence. Light can be produced by rubbing or striking a ceramic. Fracturing mica or rubbing a sphalerite crystal causes light emission. 

Electroluminescence is light emission initiated by electric influences. For example, in cathodoluminescence, the emission of light is initiated by excitation with an electron beam. Radioluminescence is caused by excitation with nnclear radiation or X-rays, whereas tribo-luminescence occurs when certain materials are mechanically altered, such as when fractured or polished. 

Materials which emit light on fracture are said to be frac-toluminescent and may be classified by their emission spectra. Nonphotoluminescent solids such as quartz, sucrose and tartaric acid have a triboluminescence spectrum indistinguishable from the 3ttu - ... 

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