Why Do Trapped Electrons Not Escape in Thermoluminescence?

  • Thread starter ctydtgat
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In summary, the trapped electrons in thermo-luminescent materials are not released by the excitation source because the trap depths are usually deeper than the energy of the excitation source.
  • #1
ctydtgat
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When thermo-luminescent materials are illuminated with UV or deep blue, luminescent centers can be excited or even ionized so that the electron gets trapped into a level just below the conduction band, typically 0.4 to 1 eV.
Why is it that the trapped electrons are not released from the trap again by the excitation source? I would expect that there are enough levels to go to high in the conduction band or at least there may be trap energies where this could happen.
Thanks!
 
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  • #2
The answer to your question is that the trap depths in thermoluminescent materials are usually too deep for the excitation source to be able to release the trapped electrons. The trap depths are typically 0.4 to 1 eV, while the energy of the excitation source (UV or deep blue) is usually much lower than this. As a result, the excitation source is not able to provide enough energy to release the electrons from the traps.
 

FAQ: Why Do Trapped Electrons Not Escape in Thermoluminescence?

What is thermoluminescence trapping?

Thermoluminescence trapping is a phenomenon in which electrons become trapped in a material's crystal lattice when it is exposed to ionizing radiation. These trapped electrons can be released through heating, resulting in the emission of light or luminescence.

How does thermoluminescence trapping work?

When a material is exposed to ionizing radiation, such as x-rays or gamma rays, electrons within the crystal lattice are excited to higher energy levels. Some of these electrons become trapped in defects or imperfections within the lattice. When the material is heated, the trapped electrons are released and emit light as they return to their original energy levels.

What is thermoluminescence dating?

Thermoluminescence dating is a technique used to determine the age of archaeological materials by measuring the amount of light emitted when they are heated. This technique relies on the fact that the amount of trapped electrons in a material increases with time, and thus the amount of light emitted upon heating can be used to estimate the age of the material.

What are some applications of thermoluminescence trapping?

Thermoluminescence trapping has several practical applications, including thermoluminescence dating in archaeology, radiation dosimetry in medical and industrial settings, and environmental monitoring of radiation levels.

How is thermoluminescence trapping different from other forms of luminescence?

Thermoluminescence trapping is different from other forms of luminescence, such as fluorescence and phosphorescence, because it involves the release of trapped electrons rather than the excitation of electrons in the material. Additionally, thermoluminescence occurs only upon heating, while fluorescence and phosphorescence can occur under various conditions.

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