Systematic errors in thermoluminescence

Ege, A.; Wang, Y.; Townsend, Peter

doi:10.1016/j.nima.2007.03.014

Cited by 31 publications

(19 citation statements)

References 19 publications

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“…This is frequently overlooked but the problem has been discussed in a number of publications. 16,[29][30][31][32] The fast heating rate data are unsuitable for kinetic analysis. A second problem is that emission bands normally broaden with increasing temperature and may vary in terms of their luminescence efficiency.…”

Section: Discussionmentioning

confidence: 99%

“…High rates are acceptable for dosimetry where only the total signal is of interest, but rapid heating results in major temperature gradients (e.g., Ref. 16) and so are inappropriate for the more fundamental investigations of the current work. The benefits of the low heating rate are of particular value for the Eu doped samples where differences in the TL exist for different emission lines.…”

Section: Methodsmentioning

confidence: 99%

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Ion size effects on thermoluminescence of terbium and europium doped magnesium orthosilicate

et al. 2015

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Thermoluminescence (TL) and radioluminescence (RL) are reported over the temperature range 25-673 K from MgSiO 4 :Tb and MgSiO 4 :Eu. The dominant signals arise from the transitions within the Rare Earth (RE) dopants, with limited intensity from intrinsic or host defect sites. The Tb and Eu ions distort the lattice and alter the stability of the TL sites and the peak TL temperature scales with the Tb and Eu ion size. The larger Eu ions stabilize the trapped charges more than for the Tb, and so the Eu TL peak temperatures are ;20% higher. There are further size effects linked to the TL driven by the volume of the upper state orbitals of the rare earth transitions. For Eu the temperatures of the TL peaks are wavelength dependent since higher excited states couple to distant traps via more extensive orbits. The same pattern of peak temperature data is encoded in RL during heating. The data imply that there are sites in which the rare earth and charge stabilizing defects are closely associated within the host lattice, and the stability of the entire complex is linked to the lattice distortions from inclusions of impurities.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Ion size effects on thermoluminescence of terbium and europium doped magnesium orthosilicate

et al. 2015

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“…Nevertheless many journal articles continue to appear with modelling based on the heater temperature, despite a number of publications which have given detailed indications of the errors involved, or empirical suggestions as to how to minimise them [2][3][4][5]. …”

Section: Thermoluminescence Dosimetrymentioning

confidence: 99%

Common mistakes in luminescence analysis

Wang

Townsend

2012

J. Phys.: Conf. Ser.

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Abstract. Luminescence techniques are powerful and sensitive probes to study imperfections, impurities and modifications of insulating materials. They are used in a wide range of disciplines from condensed matter physics to archaeology and mineralogy and the methods have developed over nearly a century. Early equipment was often not quantitative and data were collected in formats that were difficult to process and manipulate, and so signals were frequently presented in terms of the initial signals without corrections for equipment spectral sensitivity. Unfortunately not only did this distort the information but often it resulted in incorrect interpretations. Further, the incorrect data handling has persisted into modern usage both by physicists and those in other fields who merely use luminescence as a sensitive technique. Several main types of problem are considered. These include temperature errors in thermoluminescence dosimetry; subtleties in the signal intensity corrections for the responses of both the spectrometer and detectors; grating polarization effects; sample anisotropy; and common errors in spectral deconvolution, especially failure to transform from wavelength to energy plots. IntroductionLuminescence signals provide information on relaxation processes in both inorganic and biological materials and the photon energy of the transition is primarily defined by the electronic structure around the emission site. Subtle variations in the structure will then influence the transition energy and excited state lifetime. Such variations have been successfully used to track changes over volumes as large as 50 neighbouring shells. Luminescence is therefore a powerful probe of defect structures in insulators, as well as responding to impurities, phase changes and distortions such as those caused by stress or nanoparticle inclusions. Equally, the changes induced by local distortion make luminescence a useful probe to distinguish between healthy and diseased biological material and it is used in the emerging field of Optical Biopsy. Luminescence signals have been studied for more than a century with techniques from simple visual observation to black and white or colour photography. By the 1960s more quantitative detectors, such as photomultiplier tubes became available. However the spectral information was generally displayed on a chart recording as a monochromator swept through the wavelength range of the system. Such raw data were then published and used as the basis for discussion and interpretation of the luminescence. For some applications this was acceptable, for example in mineralogical applications changes in spectra revealed different component materials and the presence of rare earth ions were easily identified by characteristic line spectra. It must be recalled that in the 1960s attempts to remove the background dark current, and then scale the signals to correct for the transmission efficiency of the monochromator and sensitivity of the PM tube involved tedious manual processing (N.B. on line computer...

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“…This can be understood from a consideration of the fact that in a second order reaction, significant concentrations of released electrons are retrapped before they recombine, in this way giving rise to a delay in the luminescence emissions and a spreading out of emission over a wide range of temperature. We have attempted to make an activation energy and kinetic analysis with the model of Chen [46] and discussed the results.…”

Section: Trap Parameters Mean Valuesmentioning

confidence: 99%