On the Influence of Spatial Correlation on the Kinetic Order of TL

Radiation Protection Dosimetry

2006

Standard kinetic models for thermoluminescence (TL) relate to the simple trap model (STM) and the model of localised transitions (LT). This paper presents a review of TL properties in various spatially correlated systems (SCS), which span the two limiting cases. A classification of kinetic models for SCS is proposed. Numerical results are presented for the isolated clusters model (IC) and the interacting one-dimensional (1-D) and three-dimensional (3-D) systems. For these systems an influence of external electric field on TL is demonstrated. Analytical formulation for the IC model is possible using trap structural functions (TSFs). To calculate the TSFs (analytically or numerically) it is convenient to use their structural and symmetry properties. Analytical equations are presented also for the semi-localised transitions (SLT) model, which is a generalised version of LT. It is shown that in some cases the SLT model leads to the cascade detrapping (CD) phenomenon. The CD mechanism produces very narrow TL peaks that are apparently well described by the first order kinetics with very high frequency factors and very high activation energies.

Section: A the Model Of Isolated Clusters (Ic)mentioning

confidence: 99%

Topology-dependent thermoluminescence kinetics

Radiation Protection Dosimetry

2006

“…In this case a more complex heating profile was chosen in the form of sawtooth curve with the increasing part of 18K and decreasing 8K. The increasing regions were then analysed in terms of initial rise dependence (5). Calculated activation energies are plotted on the bottom diagrams in fig.3.…”

Section: Results Of Calculationsmentioning

confidence: 99%

Initial rise methods in the analysis of thermally stimulated relaxation phenomena

International Conference on Solid State Crystals '98: Single Crystal Growth, Characterization, and Applications

Swiatek-Prokop

1999

An accuracy of the initial rise method is considered, as applied to the determination of the activation energy from thermoluminescence (U) and thermally stimulated conductivity (TSC) spectra. The method is analysed in the classical case described by the simple trap model as well as in the presence of spatial correlation between traps. For this purpose a novel, generalised version of the Monte Carlo algorithm was developed. It allows to simulate TSR processes with an arbitrary heating function applied that gives the possibility of simulating the use of the initial rise method and the fractional glow technique. An influence of initial filling of traps on the initial rise method is analysed. It is confirmed that for sufficiently low initial concentration of charge carriers in traps the method gives correct values of the activation energies even in the case of strong retrapping. This conclusion is valid irrespective of the spatial correlation between traps and recombination centres.

“…This obviously holds true for LT and STM models. From earlier Monte Carlo simulations we learned (6,7,9) that the greatest discrepancies in TL kinetics between the IC and the two standard models take place for small clusters ( 0 10 n < ) characterized by high retrapping coefficients ( 1 r A B ≡ > ) and low density of thermally disconnected traps ( 1 M N ω = < ). For that reason in this region one may expect also possible divergence of TSFs e.g.…”

Section: A Direct Numerical Calculation -Arguments Confirming the Inmentioning

confidence: 99%

“…It was found that SCS TL shows many unexpected features that cannot be explained within the framework of LT and STM models. Examples include apparently composite structure of monoenergetic peaks (6,7) , additional 'displacement' peaks (8) and the dependence of TL on the external electric field (9,10) . For review, see the papers (11,12) .…”

Section: Introductionmentioning

confidence: 99%

Calculation and properties of trap structural functions for various spatially correlated systems

Radiation Protection Dosimetry

2006

Thermoluminescence (TL) kinetics in spatially inhomogeneous systems can be studied by various Monte Carlo algorithms. Recently, a new analytical approach was suggested for the isolated cluster model. The theory is based on the concept of trap structural functions (TSFs). TSFs depend solely on topological properties of solids. Therefore, knowing TSFs for traps and recombination centres it is possible to calculate TL for various parameters, e.g. different heating schemes and different energy configurations. This paper presents some properties and methods of calculation of TSFs. Structural character of TSFs is verified numerically. It is shown that for simple cluster systems it is possible to calculate the functions analytically.