Principles of thermoluminescence dating
Included is a discussion of the interaction of alpha particles, beta rays (energetic electrons), and gamma rays with solids, particularly electron-hole ion pair formation, and the trapping of charges by crystal imperfections.Also described is the charge-release process induced by heating and the accompanying emission of luminescence resulting from charge recombination and retrapping.
Free electrons, excited mainly by environmental alpha, beta and gamma radiation, become trapped within the crystalline defects of minerals such as quartz and feldspar, and continue to accumulate until exposure to daylight or sufficient heat evicts them, bleaching the sample of its signal, and effectively resetting the ‘luminescence clock’ to zero.
The radiation causes charge to remain within the grains in structurally unstable "electron traps".
The trapped charge accumulates over time at a rate determined by the amount of background radiation at the location where the sample was buried.
Thermoluminescence is particularly useful to archaeologists as it provides a means of dating non-organic material such as ceramics and that it can be applied before 50,000 years ago (although not to pottery as there isn't any), beyond the effective range of radiocarbon dating.
It has been extensivly applied to burnt flint and in many cases has an advantage over other dating methods as the zero event (heating) is often a direct result of use of manufacture.