Luminescence dating techniques gayfishdating com

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.Stimulating these mineral grains using either light (blue or green for OSL; infrared for IRSL) or heat (for TL) causes a luminescence signal to be emitted as the stored unstable electron energy is released, the intensity of which varies depending on the amount of radiation absorbed during burial and specific properties of the mineral.Most luminescence dating methods rely on the assumption that the mineral grains were sufficiently "bleached" at the time of the event being dated.The radiation causes charge to remain within the grains in structurally unstable "electron traps".The trapped charge accumulates over time at a rate determined by the amount of background radiation at the location where the sample was buried.

These slowly decay over time and the ionizing radiation they produce is absorbed by mineral grains in the sediments such as quartz and potassium feldspar.It uses various methods to stimulate and measure luminescence It includes techniques such as optically stimulated luminescence (OSL), infrared stimulated luminescence (IRSL), and thermoluminescence (TL)."Optical dating" typically refers to OSL and IRSL, but not TL.This phenomenon forms the basis of thermoluminescence and optical dating.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).Luminescence dating (including thermoluminescence and optically stimulated luminescence) is a type of dating methodology that measures the amount of light emitted from energy stored in certain rock types and derived soils to obtain an absolute date for a specific event that occurred in the past.

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