Thermoluminescence dating is the determination of the date at which materials were formed by measuring the light energy released when heating it.

The natural flux of ionizing radiation— both from cosmic radiation and from natural radioactivity—can put crystalline structures in excited states, storing some of the energy of the radiation. A very small fraction can stay in these excited states for long time. When such material is heated, the stored energy is released as weak light (luminescence), the so-called thermoluminescence. After cooling, re-heating of the material will not generate light, as no excited states remain.

Thermoluminescence dating is used for material where radiocarbon dating is not available, like sediments. Its use is now common in the authentication of old ceramic wares, for which it gives the approximate date of the last firing.

References

• Quaternary TL Surveys - Guide to thermoluminescence date measurement http://www.users.globalnet.co.uk/~qtls/