When a radiation is incident on a material, some of its energy may be absorbed and re-emitted as light of longer wavelength. 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. Energy absorbed from ionising radiation alpha, beta, gamma, cosmic rays frees electrons to move through the crystal lattice and some are trapped at imperfections in the lattice.
Quick Answer: What Is Thermoluminescence Dating Used For?
Absolute dating - Wikipedia
Luminescence dating including thermoluminescence and optically stimulated luminescence is a type of dating methodology that measures the amount of light emitted from energy stored in certain rock types and derived soils to obtain an absolute date for a specific event that occurred in the past. The method is a direct dating technique , meaning that the amount of energy emitted is a direct result of the event being measured. Better still, unlike radiocarbon dating , the effect luminescence dating measures increases with time. As a result, there is no upper date limit set by the sensitivity of the method itself, although other factors may limit the method's feasibility.
Thermoluminescence Dating of Ceramics
Thermoluminescence dating TL is the determination, by means of measuring the accumulated radiation dose, of the time elapsed since material containing crystalline minerals was either heated lava , ceramics or exposed to sunlight sediments. As a crystalline material is heated during measurements, the process of thermoluminescence starts. Thermoluminescence emits a weak light signal that is proportional to the radiation dose absorbed by the material. It is a type of luminescence dating. Sediments are more expensive to date.
Luminescence dating depends on the ability of minerals to store energy in the form of trapped charge carriers when exposed to ionising radiation. Stimulation of the system, by heat in the case of thermoluminescence TL , or by light in the case of photo-stimulated luminescence PSL , or optically stimulated luminescence OSL. Following an initial zeroing event, for example heating of ceramics and burnt stones, or optical bleaching of certain classes of sediments, the system acquires an increasing luminescence signal in response to exposure to background sources of ionising radiation.