Triboluminescence (TL) is the light emitted from a material when it undergoes fracture. While this unique phenomenon has been known for over 400 years, no theory has yet to predict whether a material will emit TL. However, this has not stopped scientists from coming up with many unique applications. One such application is the use as the active element for impact and damage sensors. Around the turn of the 21^stcentury, researchers used TL to patent a sensor capable of discerning the locations of an impact. Their simple design involved coating a structure with a triboluminescent material or creating a composite triboluminescent object. A sensor would then be embedded within the structure or mounted on its surface. Impacts to the structure would produce light, which would be recorded and analyzed to determine the location. In addition, researchers proposed that several different triboluminescent materials could be used and arranged at various locations. The advantage is that when an impact takes place, its location could be determined by the wavelength emitted. For example, by placing two different triboluminescent materials at known distances from the detector, it is possible to determine the approximate location of the impact by measuring the emitted wavelength.

Material property measurements such as triboluminescent yield and the prompt fluorescence decay time are important considerations for any luminescent material. TL emission has to be sufficiently bright, so that the light signal reaching from the point of fracture to the detector, through a fiber optics cable, is strong enough to be detected. The majority of the known triboluminescent materials do not emit light with sufficient intensity to allow detection with compact and inexpensive detectors. A few materials, such as Europium tetrakis dibenzoylmethide triethylammonium (EuD₄TEA), is bright enough to be seen in daylight and has more than twice the triboluminescent emission yield of zinc sulfide doped with manganese (ZnS:Mn) when subjected to low energy impacts. Research has also shown that adding specific dopants to EuD₄TEAcan increase the triboluminescent emission yield by more than a factor of five over ZnS:Mn, which is often used as a basis for comparison.In fact, EuD₄TEA has been found to be one of the brightest known TL materials and is a potential candidate for application as an impact sensor.

The purpose of this presentation is to present results from recently completed light yield and prompt fluorescence decay time measurements for EuD₄TEA. Emphasis will be placed on current efforts to utilize this data for a variety of potential applications to measure impacts in extreme environments. Basically, EuD₄TEA is a material solution looking for a problem.