Luminescence is emission of light by a substance not resulting from heat; it is thus a form of cold-body radiation.
It can be caused by chemical reactions, electrical energy, subatomic motions, or stress on a crystal, which all are ultimately caused by Spontaneous emission.
Radiometric dating is a technique used to date materials based on a knowledge of the decay rates of naturally occurring isotopes, and the current abundances.
It is our principal source of information about the age of the Earth and a significant source of information about rates of evolutionary change.
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".
More slowly decaying isotopes are useful for longer periods of time, but less accurate in absolute years.
Additionally, elements may exist in different isotopes, with each isotope of an element differing only in the number of neutrons in the nucleus.
A particular isotope of a particular element is called a nuclide. That is, at some random point in time, an atom of such a nuclide will be transformed into a different nuclide by the process known as radioactive decay.
It can be caused by chemical reactions, electrical energy, subatomic motions, or stress on a crystal.
The term 'luminescence' was introduced in 1888 by Eilhard Wiedemann.