Thermoluminescence dating presupposes a "zeroing" event in the history of the material, either heating (in the case of pottery or lava) or exposure to sunlight (in the case of sediments), that removes the pre-existing trapped electrons.
Different materials vary considerably in their suitability for the technique, depending on several factors.Subsequent irradiation, for example if an x-ray is taken, can affect accuracy, as will the "annual dose" of radiation a buried object has received from the surrounding soil.Ideally this is assessed by measurements made at the precise findspot over a long period.For artworks, it may be sufficient to confirm whether a piece is broadly ancient or modern (that is, authentic or a fake), and this may be possible even if a precise date cannot be estimated.Where there is a dip (a so-called "electron trap"), a free electron may be attracted and trapped.
The flux of ionizing radiation—both from cosmic radiation and from natural radioactivity—excites electrons from atoms in the crystal lattice into the conduction band where they can move freely.
Both thermoluminescence (TL) determinations on fine-grained sediment (4–11 μm) and C determinations on various organic fractions of paleosols from the profile have provided an extremely useful chronological framework for these sequences.
These sequences indicate a weakened summer monsoon during the last glacial maximum followed by a strengthening of the summer monsoon, beginning C determinations on the humin fraction of the organic component near the top of the lower paleosol and the base of the upper paleosol complex gave ages of 10.2 and 10.9 ka cal BP, respectively.
An example of this can be seen in Rink and Bartoll, 2005.
Thermoluminescence dating was modified for use as a passive sand migration analysis tool by Keizars, et al., 2008 (Figure 3), demonstrating the direct consequences resulting from the improper replenishment of starving beaches using fine sands, as well as providing a passive method of policing sand replenishment and observing riverine or other sand inputs along shorelines (Figure 4).
It will often work well with stones that have been heated by fire.