Optically stimulated luminescence dating wiki

I understand what a positively- or negatively-charged defect in the lattice is.I understand that heating or light will give the trapped electron living in the positively-charged defect the energy to get up and go. But: I don't understand the processby which the negatively-charged lattice defectbecame positively-charged enoughto attract the electronthat just left the positively-charged lattice defect.Until now we were only talking about perfect crystals. There might be an atom missing, there might be an additional one. These defects not only stand out in the spatial structure but also in the electronic. Some are usually occupied, others are usually empty. What's happening during OSL is that an electron spatially trapped in one of these localized states is excited by light into an empty band and can now move around the crystal and find an equally trapped hole. Think of it this way - in an infinite lattice, the lowest energy state is one where the lattice has zero charge. The electrons live in the interstitials between atoms, and at any given point, the charge is zero. First, there's a hole created in the structure (thus the name, electron hole).Second, where there used to be zero charge, there is now a charge because 0 (no charge) minus one negative charge (the electron) results in a positively charge spot (0 - -1 = 1).A proper description of the electronic structure can no longer only look at the individual atoms. You have some certain occupied bands and higher unoccupied ones. These bands are usually well separated in energy meaning an electron can't have an energy that's between bands.One major difference now is that these bands are delocalized in space.

A good, clear graphic on the European Geosciences Union web pages explains how it works in general terms (link: https://eu/divisions/cl/tag/optically-stimulated-luminescence/).

a personal radiation monitoring device similar to the thermoluminescence dosimeter but using aluminum oxide to absorb the energy of x-rays and a laser rather than heat to release the stored energy and measure the dose of ionizing radiation received.

Optically stimulated luminescence (OSL) can be used to date Quaternary and late Pleistocene sediments.

You're probably familiar with the electronic structure of an atom with its different energy levels.

In this atom in the ground state you have levels that are occupied by electrons up to a certain level depending on the element you're looking at. They are unoccupied but they are well defined states making it possible to excite an electron into them, lifting it from its previous state up there (Up and down meaning more or less energy).

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