Triboluminescence mechanism

Triboluminescence Mechanical shaking, rubbing or crushing Crack detection in composite materials... 

Mechanoluminescence or triboluminescence arises from the mechanical action on solids lyoluminescence is where the emission of light occurs when a material goes into solution. Thermoluminescence is observed during the heating of a solid that has previously absorbed energy from radiation, as ions trapped in the solid recombine. (See also Glossary for an explanation of the terms.)... 

Mechanoluminescence arises from mechanical action on solids (also called piezoluminescence or triboluminescence). 

The triboluminescence spectrum can provide information about severalsteps in the mechanism. Figure 2a shows a typical tribolumi-... 

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 . 

Rare-earth diketonates incorporated into polymers that result in new triboluminescent materials have been investigated by Takada and coworkers . Although some RE + compounds exhibit no TL in powder form, the TL phenomenon has been observed when these compounds are dispersed in a polymer matrix and the TL mechanism is adduced to electron impact caused by discharge due to a high electric field arising from frictional electrification between the fihn and the substrate. 

Triboluminescence (from the Greek word, tribos, a rubbing) is luminescence that is produced by a mechanical shock to a crystal. It is readily observed in striking or grinding sugar crystals. 

A fimdamental difference between trlbolumlnescence and the stress-enhanced chemiluminescence of polymers, i.e., stress chemiluminescence, should be distinguished. The triboluminescence phenomenon (8) is restricted to radiation emitted during mechanical deformation. Independent of the oxygen concentration. 

The spectrum of the triboluminescence (i.e. emission caused by mechanical stress) of U0a(N03)2,6H20 is similar to that for photo-induced luminescence.167 Possible causes for this effect are electrical excitation (i.e. pressure-induced electrochemiluminescence), intermolecular interactions, and intramolecular deformations. Arguments are presented to show that the third mechanism is not important in this case. Other relevant publications are concerned with electrochemiluminescence of UOa8+ in perchloric acid,168 170 171 173 174 absorption and luminescence spectra of UOa2+ in solution,16 and detailed analyses of the emission spectrum of crystalline UOa2+ salts at low temperatures.170-174... 

Fireflies and many other animals emit radiation by chemiluminescence. In this process, chemicals mix and produce light as one of the products of reaction. Many solids emit light when crushed, a manifestation of triboluminescence. There are no general mechanisms for luminescence, and each type needs to be treated independently. 

Luminescence includes phenomena such as fluorescence and phosphorescence. It comes from the radiative deactivation of excited matter following an excitation (the mechanism of the excitation, as well as fluorescence and phosphorescence is explained below). The excitation can come from light (photoliuninescence), electricity (electroluminescence), a chemical reaction (chemoluminescence or bioluminescence, if the reaction takes place in a biological system), or a mechanical stress (triboluminescence). We focus on photoluminescence, because most of the other excitation sources require special conditions and are, with the exception of electroluminescence, quite rare, especially when dealing with the luminescence of the lanthanides. 

The specific volumes and coefficients of refraction have been calculated for aqueous solutions of sucrose at several temperatures. Self-diffusion coefficients have been reported for sucrose, sodium D-glucuronate, and 2-amino-2-deoxy-D-glucose hydrochloride in aqueous solution. The triboluminescence (i.e. luminescence caused by mechanical stress) of crystalline mono- and di-saccharides has been studied this phenomenon was shown by some sugars (e.g. sucrose and D-glucose) but not by others (e.g. cellobiose and D-mannose). An e.s.r. spectroscopic study of D-glucose, D-mannose, D-galactose, D-fructose, and methyl... 

The triboluminescence spectra of the europium(III) complexes are very similar to the corresponding solid-state photoluminescence spectra. The triboluminescence is in general weaker than the photoluminescence and only the most intense transitions of the photolu-minescence spectrum can be observed in the triboliuninescence spectrum. The other transitions are too weak to be observed. Thus europium(lll) complexes exhibit a red triboluminescence due to the Dq F2 transitiom The difference in luminescence intensity between triboluminescence and photoluminescence may result from the different excitation mechanisms triboluminescence results from excitation by mechanical stress and photoluminescence from excitation by ultraviolet radiation (Chen et al., 2001). Triboluminescence most likely occurs inside the Ctystal as cracks are formed and the triboluminescence... 

---