What is luminescence

Luminescence is an emission of ultraviolet, visible or infrared photons from an electronically excited species. The word luminescence, which comes from the Latin (lumen = light) was first introduced as luminescenz by the physicist and science historian Eilhardt Wiedemann in 1888, to describe all those phenomena of light which are not solely conditioned by the rise in temperature , as opposed to incandescence. Luminescence is cold light whereas incandescence is hot light. The various types of luminescence are classified according to the mode of excitation (see Table 1.1). 

Ionizing radiation (X-rays, a, / , y) Cathode rays (electron beams) Electric field 

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