Experimental evidence of triboluminescence induced by hypervelocity impact

The emission of light due to crystal fracture, or triboluminescence (TL), is a phenomenon that has been known for centuries. One of the most common examples of TL is the flash created from chewing wintergreen Lifesavers(R). For the last couple of years, the authors have been measuring fluorescence properties of phosphors like zinc sulfide doped with manganese (ZnS:Mn). Preliminary results indicate that impact energies greater than 16 mJ produced measurable TL from ZnS:Mn. Light was generated from the interaction of a dropped mass and a small number of luminescence centers in the ZnS:Mn powder. To extend this research, a two-stage hypervelocity light gas gun located at NASA's Marshall Space Flight Center (MSFC) was used to evaluate equipment and settings that show promise for hypervelocity TL detection. In these experiments, a projectile was accelerated to approximately 5-6 km/s before striking a ZnS:Mn phosphor-coated aluminum plate. This paper will provide an overview into the first experimental evidence of TL emission from ZnS:Mn due to hypervelocity impact. It is hoped that these results will generate interest in future hypervelocity research. (C) 2006 Published by Elsevier Ltd.