When scientists pull pottery from the ground, they use heat or lasers to de-excite these electrons out of their trap states back to their original state. Scientists measure the amount of light to get the total measured radiation dose (TMRD).They divide this by an assumed radiation dose rate (RDR) to estimate the pottery’s age.These charge defects are potential sites of electron storage with a variety of trap-depth energies.A subpopulation of stored electrons with trap depths of ~1.3 to 3 e V is a subsequent source for time-diagnostic luminescence emissions. One possible approach is to use coastal marine sand identified as Eemian by an examination of the palaeoecology.The Eemian period in northern Europe is considered to last from 132 to 116 ka; marine samples are likely to be linked most closely to at least part of this period, and modern coastal sands are known to be well bleached.
We analyse the quartz or feldspar minerals in sand deposits.
95% reduction in OSL within 4 seconds of exposure to light from blue diodes Optically stimulated luminescence (OSL) dating or optical dating provides a measure of time since sediment grains were deposited and shielded from further light or heat exposure, which often effectively resets the luminescence signal (Fig.1).
This technique, as thermoluminescence, was originally developed in the 1950s and 1960s to date fired archaeological materials, like ceramics (Aitken, 1985).
If we assume that the radiation dose rate of the sediment has remained constant over time, then if we measure that dose rate, we can calculate the sample age.
Hollie Wynne (Aberystwyth University) stirs OSL samples being treated with acid in the preparation lab of the Aberystwyth Luminescence Research Laboratory. We make an approximation of the number of trapped electrons by measuring the light that they emit following stimulation by light (hence the name of the technique, “Optically stimulated luminescence”).