TY - JOUR

T1 - On the Quasi-equilibrium assumptions in the theory of thermoluminescence (TL)

AU - Chen, R.

AU - Pagonis, V.

PY - 2013

Y1 - 2013

N2 - The phenomenon of thermoluminescence (TL) is governed by a set of simultaneous differential equations. When one studies the properties of a single peak, resulting from the thermal release of electrons from a trap into the conduction band, followed by radiative recombination with holes in centers, the set consists of three non-linear equations. Even in this simple case, the equations cannot be solved analytically. In order to get approximate solutions, the conventional way has been to make the "quasi-equilibrium" assumptions, namely that 9dnc/dt9 is significantly smaller than 9dn/dt9 and 9dm/dt9, where n and m are the occupancies of traps and centers, respectively, nc is the concentration of electrons in the conduction band, and nc{n; nc{m. We show, using simulations as well as analytical arguments that the former condition often does not occur; however, its consequences are valid. The reason is that the conventional quasi-equilibrium assertion must be replaced by a different condition. As for the smallness of the concentration of free electrons, we show that it may not be fulfilled at the high-temperature end of a single glow peak or in the highest-temperature peak in a series. In some cases, this condition results in a broad high-temperature tail of the TL peak, as previously observed experimentally in several materials.

AB - The phenomenon of thermoluminescence (TL) is governed by a set of simultaneous differential equations. When one studies the properties of a single peak, resulting from the thermal release of electrons from a trap into the conduction band, followed by radiative recombination with holes in centers, the set consists of three non-linear equations. Even in this simple case, the equations cannot be solved analytically. In order to get approximate solutions, the conventional way has been to make the "quasi-equilibrium" assumptions, namely that 9dnc/dt9 is significantly smaller than 9dn/dt9 and 9dm/dt9, where n and m are the occupancies of traps and centers, respectively, nc is the concentration of electrons in the conduction band, and nc{n; nc{m. We show, using simulations as well as analytical arguments that the former condition often does not occur; however, its consequences are valid. The reason is that the conventional quasi-equilibrium assertion must be replaced by a different condition. As for the smallness of the concentration of free electrons, we show that it may not be fulfilled at the high-temperature end of a single glow peak or in the highest-temperature peak in a series. In some cases, this condition results in a broad high-temperature tail of the TL peak, as previously observed experimentally in several materials.

KW - Broad tail

KW - Quasi-equilibrium assumption

KW - Thermoluminescence

UR - http://www.scopus.com/inward/record.url?scp=84884903710&partnerID=8YFLogxK

U2 - 10.1016/j.jlumin.2012.07.019

DO - 10.1016/j.jlumin.2012.07.019

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AN - SCOPUS:84884903710

SN - 0022-2313

VL - 143

SP - 734

EP - 740

JO - Journal of Luminescence

JF - Journal of Luminescence

ER -