Related to thermoluminescence: thermoluminescence dosimetry. A phenomenon in which certain minerals release previously absorbed radiation upon being moderately heated. All rights reserved. It is caused by pre-irradiation of the material inducing defects which are removed by the heat, the energy released appearing as light: used in archaeological dating. Copyright , , by Random House, Inc.
Thermoluminescence dating pronunciation
Thermoluminescence TL dating is the determination, by means of measuring the accumulated radiation dose, of the time elapsed since material containing crystalline minerals was either heated lava , ceramics or exposed to sunlight sediments. As the material is heated, during measurements, thermoluminescence , a weak light signal, is emitted, proportional to the radiation dose absorbed by the material. Natural crystalline materials contain imperfections: impurity ions , stress dislocations, and other phenomena that disturb the regularity of the electric field that holds the atoms in the crystalline lattice together. This leads to local humps and dips in its electric potential. Where there is a dip a so-called " electron trap" , a free electron may be attracted and trapped. The flux of ionizing radiation—both from cosmic radiation and from natural radioactivity —excites electrons from atoms in the crystal lattice into the conduction band where they can move freely. Most excited electrons will soon recombine with lattice ions, but some will be trapped, storing part of the energy of the radiation in the form of trapped electric charge Figure 1.
Carbon-14 dating easy definition
There are many different methods that are used to determine the age of archaeological artifacts, and each method measures something the others cannot. To name a few; radiocarbon dating measures the decay of carbon in biological substances, obsidian hydration measures the amount of water absorbed by an artifact made of obsidian, and thermoluminescence measures the stored energy in the lattice of stone. Each method is completely different from the next but all of them find the same thing.
When a radiation is incident on a material, some of its energy may be absorbed and re-emitted as light of longer wavelength. The wavelength of the emitted light is characteristic of the luminescent substance and not of the incident radiation. Thermoluminescence TL is the process in which a mineral emits light while it is being heated: it is a stimulated emission process occurring when the thermally excited emission of light follows the previous absorption of energy from radiation. Energy absorbed from ionising radiation alpha, beta, gamma, cosmic rays frees electrons to move through the crystal lattice and some are trapped at imperfections in the lattice.