Luminescence is a spontaneous emissionofradiation from an electronically or vibrationally excited species not in thermal equilibrium with its environment. [1] A luminescent object emits cold light in contrast to incandescence, where an object only emits light after heating.[2] Generally, the emission of light is due to the movement of electrons between different energy levels within an atom after excitation by external factors. However, the exact mechanism of light emission in vibrationally excited species is unknown.
The dials, hands, scales, and signs of aviation and navigational instruments and markings are often coated with luminescent materials in a process known as luminising.[3]
Luminescence occurs in some minerals when they are exposed to low-powered sources of ultravioletorinfrared electromagnetic radiation (for example, portable UV lamps) at atmospheric pressure and atmospheric temperatures. This property of these minerals can be used during the process of mineral identification at rock outcrops in the field or in the laboratory.
The term luminescence was first introduced in 1888.[9]
