Excerpt from: URL: http://www.chem.missouri.edu/Chem2400/lab/E4.htm
Triboluminescent Manganese Compounds
(adapted from write-up by S. Jurisson)
The occurrence of triboluminescence (sometimes called mechanoluminescence) has been known for centuries. Triboluminescence is the luminescence that occurs from the application of mechanical stress to crystals. Triboluminescence occurs in both organic and inorganic materials, with sucrose being a prime example of an organic material that exhibits this property.
Understanding what conditions result in triboluminescence and identifying the species that is emitting has only come to light in the last few decades. Work reported by Zink et al. in 1976 on the “Triboluminescence of Sugars” showed that the triboluminescence resulted from the excitation of trapped nitrogen gas during mechanical grinding of some sugars (D-glucose, lactose, maltose, L-rhammose, sucrose).1 It is generally accepted that the excitation energy to generate the triboluminescent emission comes from very high local electric fields generated when the crystals fracture.2
Cotton recently reported that the crystals that fracture must be noncentrosymmetric, so that the opposite sides of a crack can be oppositely charged.3 They evaluated a variety of tetrahedral manganese(II) compounds to correlate triboluminescence with their structures (centrosymmetric or noncentrosymmetric). They evaluated 11 Mn(II) compounds and found that only the six compounds that formed noncentrosymmetric crystals triboluminesce.3 You will be making two of the Mn(II) compounds that triboluminesce and investigating this very interesting property.
1. J.I. Zink, G.E. Hardy, J.E. Sutton “Triboluminescence of Sugars”, J. Phys. Chem. 1976, 80, 248-9.
2. J.T. Dickinson, L.B. Brix, L.C. Jensen “Electron and Positive Ion Emission Accompanying Fracture of Wint-o-green Lifesavers”, J. Phys. Chem. 1984, 88, 1698-1701.
3. F.A. Cotton, L.M. Daniels, P. Huang “Correlation of Structure and Triboluminescence for Tetrahedral Manganese(II) Compounds”, Inorg. Chem. 2001, 40, 3576-3578.