Luminescence dating in archaeology from origins to optical
The lighting level in the luminescence laboratory is low and usually red, similar to the conditions in a photographic darkroom.
The grains, 90–300 μm in diameter (sand sized), are usually extracted from the bulk sediment sample by wet or dry sieving and are then chemically treated with hydrochloric (HCl) acid to remove carbonates and hydrogen peroxide (H) solution to digest any organic matter.
Bøtter-Jensen and Duller (The OSL dating technique is based on the fact that natural minerals (such as quartz and feldspar) are not perfectly formed but contain defects in their crystal lattices that are able to trap negatively charged electrons within positively charged vacancies (“holes”).
In this instance, the duration of burial in the absence of sunlight can provide ages for site occupation, the manufacture of artifacts, and the accumulation of faunal remains, all inferred from the depositional age of the associated surrounding sediments being dated.
The first archaeological application was published by Rhodes (), who used the method to analyze quartz grains from three archaeological sites (Chaperon Rouge, Skhirat, and Tahadart) in Morocco.
These mineral grains can be likened to rechargeable batteries (Figure Th and its decay products) from within the sample and also external to the sample in the surrounding soil. While buried in the ground and hidden from sunlight, these “batteries” trap and store electrons as particles emitted from unstable radioactive atoms move them out of their normal orbital locations.
In this way, the trapped electrons become more numerous and accumulate energy at a predictable rate over time (Figure 400 °C).