Thermoluminescence dating laboratory
Luminescence dating of sediment relies upon the fact that the geological luminescence signal of the sediment is reduced to a near-zero residual due to exposure to daylight during weathering and transport (see Aitken, 1985, 1998).
Trapping: Upon exposure to nuclear radiation, some bound electrons of the atoms making up a mineral's lattice are detached from their parent nuclei and become freely mobile: they are said to enter the conduction band.
Structural defects in the lattice (vacancies, interstitial atoms, and substitutional impurities) create localized charge deficits, which act as traps T for the conduction electrons.
Most electrons recombine or are briefly trapped in very shallow traps, but a few are trapped at deep traps and remain there over geological time-scales (1-1000 Ma).
The now charge-deficient ion that contributed the trapped charge becomes a luminescence center L Recombination: Electrons trapped in deep traps T do not readily recombine unless induced to do so by natural "clock-resetting events", or under strictly controlled laboratory conditions.
Heat or light can eject charges from traps T back into the conduction band.This measured signal provides a measure to the palaeodose received in the intervening period of burial.