Thermo luminescence dating
A non-negligible part of materials which ceramic is usually made of (like quartz and feldspars) is thermoluminescent: those materials have trap states that can capture electrons after interaction with alfa, beta and gamma rays existing in nature.When these materials are heated to several hundreds of Centigrade degrees, electrons are evicted from trap states and energy is emitted in form of light: thermoluminescence (TL).Luminescence dating is particularly appropriate when radiocarbon dating is not possible (either where no suitable material is available or for ages beyond the radiocarbon age limit) or for applications affected by radiocarbon plateau effects (e.g.post 1700 AD, early Iron Age contexts, late glacial timescales) and when the relationship between the organic materials and the archaeological context is uncertain.If the heating rate is linear and if we suppose the probability of a second trapping to be negligible with respect to the probability of a recombination, the TL intensity is related to the activation energy of the trap level by a known expression. Thermoluminescence can be used to date materials containing crystalline minerals to a specific heating event.This is useful for ceramics, as it determines the date of firing, as well as for lava, or even sediments that were exposed to substantial sunlight.The wavelength of the emitted light is characteristic of the luminescent substance and not of the incident radiation.Thermoluminescence (TL) is the process in which a mineral emits light while it is being heated: it is a stimulated emission process occurring when the thermally excited emission of light follows the previous absorption of energy from radiation.
An input of energy, such as heat, is required to free these trapped electrons.
The age range for pottery and other ceramics covers the entire period in which these materials have been produced.