A general term which describes any process in which energy is emitted from a material at a different wavelength from that at which it is absorbed. It is an umbrella term covering fluorescence, phosphorescence, and triboluminescence.
Luminescence phenomena often occur only in the presence of a trace amount of an activator species (such as iron in the case of manganese-containing salt from the Saltan Sea), which causes the manganese and lead to interact quantum mechanically to give an excited manganese state which would otherwise be inaccessible. Quenchers such as iron and copper may also destroy luminescence. A final source of luminescence can be lattice defects in materials such as diamonds.
Chemiluminescence, Fluorescence, Triboluminescence
References
Blasse, G. and Grabmaier, B. C. Luminescent Materials. New York: Springer-Verlag, 1995.
Harvey, E. N. A History of Luminescence. Philadelphia: American Philosophical Society, 1957.
Weisstein, E. W. "Books about Luminescence." http://www.ericweisstein.com/encyclopedias/books/Luminescence.html.
