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1.
Superlinear dose dependence of thermoluminescence (TL) and optically stimulated luminescence (OSL) has been reported for many materials. The theoretical explanation has been ascribed to competition of either traps or recombination centers, during the excitation stage or during the read-out phase. There has been an account in the literature on superlinearity of OSL associated with merely one trapping state and one kind of recombination center. This had to do with the process taking place during the read-out stage, namely the optical stimulation. In the present work, we report on a model of one trapping state and one kind of recombination center which results in a superlinear filling of the center. Thus, one can expect a superlinear dose dependence of the area under the resulting TL glow peak as well as the OSL signal. We follow this situation by writing the simultaneous nonlinear rate equations for the one-trap-one-recombination-center (OTOR) model and study the expected results by numerical simulation consisting of solving the equations with sets of the trapping parameters. We also present analytical results based on simplifying assumptions, and compare the analytical and numerical results. The effect is significant at relatively high dose rates. The main implication is that when one tries to evaluate by TL dosimetry a dose applied at a high rate, calibration of the TL dosimeter using much smaller dose rates may result in inaccurate results. 相似文献
2.
The sublinearity of dose characteristics of the thermoluminescence has been calculated in terms of the model of competitive interaction of electron and hole trapping centers. It has been found that the sub-linearity is caused by the nonradiative electron recombination with hole deep traps during irradiation and recording of the thermoluminescence upon linear heating of a dosimetric phosphor. It has been shown that the proposed sublinearity mechanism can be used to explain the dose characteristics of the thermoluminescence of anion-defective aluminum oxide. 相似文献
3.
A. L. Apanasenko A. V. Kuznichenko Yu. B. Govyadovskii V. G. Yakunin 《Journal of Applied Spectroscopy》1991,54(3):271-276
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 3, pp. 438–444, March, 1991. 相似文献
4.
V. S. Kortov I. I. Milman S. V. Nikiforov E. V. Moiseĭkin 《Physics of the Solid State》2006,48(3):447-452
The mechanism of formation of nonlinearity in the dose dependence of the thermoluminescence output was investigated for anion-defect α-Al2O3 single crystals. The experiments revealed a new specific feature: the nonlinearity of the dose dependence of the thermoluminescence output depends on the heating rate of crystals during recording of thermoluminescence. It was established that this effect and other thermoluminescence features studied earlier for anion-defect α-Al2O3 crystals are adequately described in the framework of a unified mechanism associated with the interactive interaction of dosimetric and deep traps. Recommendations are given for a decrease in the range of the superlinear portion in the dose dependence of the thermoluminescence output for the crystals under investigation. 相似文献
5.
6.
M. Buck L. Wischmeier S. Schumacher G. Czycholl F. Jahnke T. Voss I. Rückmann J. Gutowski 《The European Physical Journal B - Condensed Matter and Complex Systems》2004,42(2):175-180
A theory-experiment comparison for the intensity and polarization dependence of spectrally resolved transient four-wave-mixing signals is presented for a ZnSe single quantum well. Results for high intensities deviate from a simple model based on the optical Bloch equations for a five-level system whereas a microscopic theory for coherent excitonic and biexcitonic nonlinearities shows excellent agreement.Received: 8 July 2004, Published online: 14 December 2004PACS:
71.35.-y Excitons and related phenomena - 78.47. + p Time-resolved optical spectroscopies and other ultrafast optical measurements in condensed matter 相似文献
7.
The specific features revealed in the superlinearity of dose dependences of thermoluminescence of anion-defective aluminum oxide single crystals have been considered theoretically in terms of the model of an interactive trap system. The model explains the decrease in the degree of superlinearity at a low heating rate, as well as with an increase in the dose increment, the occupancy of deep traps, and the sensitivity of the crystals to radiation due to the increase in the concentration of luminescence centers. The obtained results indicate a widening of the possibilities of the model for interpreting experimental data in the investigation of the dose characteristics of thermoluminescence of the studied crystals. 相似文献
8.
The fast, linearly modulated optically stimulated luminescence (LM-OSL) component in quartz is the main dosimetric signal used for the dating applications of this material. Since the blue light stimulation (470 nm, 40 mW cm ) time needed to obtain the fast LM-OSL component is less than 50 s the electron trapping levels responsible for it are still highly populated. In this way an active radiation history is created which could play an important role in the dosimetric characteristics of the fast OSL signal. In the present work the dose response behavior of the fast OSL signal is investigated in quartz samples with an annealed radiation history and quartz samples possessing an artificial radiation history. A computerized curve de-convolution analysis of the LM-OSL curves for 50 s stimulation time showed that it consists of three individual OSL components. The faster component C1 with peak maximum time around 5 s has a linear dose response in virgin samples, which turns to a slight superlinearity as a function of the artificial radiation history. On the other hand the component C2 with peak maximum time at 12 s is slightly superlinear which turns into strong superlinearity as a function of artificial radiation history. Finally, component C3 with peak maximum time at about 45 s is strongly superlinear for both virgin samples and as a function of artificial radiation history. The implications to practical application are discussed. 相似文献
9.
In this study, the various dosimetric properties of the thermoluminescent (TL) phosphor of CaF2:natural including response characteristics, sensitivity to thermal annealing and decay of stored energy were investigated in detail. The analysis of the peak temperature values and the half widths of the resolved components in the glow curves, by using the Computerized Glow Curve Deconvolution (CGCD) Method, resulted in the activation energy (E) of 0.85–1.83 eV and frequency factor (s) of 6.17E+9–2.90E+15 s?1. The effects of pre-irradiation thermal annealing on the radiation-induced sensitization of the thermoluminescent response of CaF2:natural were presented. An enhancement of sensitivity after being subjected to a high beta particle exposure was clarified. The effect was complicated by the influence of heat treatments before the exposure to radiation. Replicate runs on CaF2:natural after irradiation with 1 Gy absorbed dose indicated good reproducibility of peak temperatures and intensities; they can be re-used for repeated measurements. It appeared that the main dosimetric peak at 280 °C exhibits negligible fading over 4 weeks and may be used for dosimetry. This study has demonstrated that the potential exists for the use of CaF2:natural for TL radiation dosimetry. 相似文献
10.
《Radiation measurements》2007,42(9):1441-1452
The dose response of the Ge- and Ti-centres in quartz is studied over a large dose range. After an initial signal increase in the low dose range, both defects show a pronounced decrease in signal intensities for high doses. The model by Euler and Kahan [1987. Radiation effects and anelastic loss in germanium-doped quartz. Phys. Rev. B 35 (9), 4351–4359], in which the signal drop is explained by an enhanced trapping of holes at the electron trapping site, is critically discussed. A generalization of the model is then developed, following similar considerations by Lawless et al. [2005. A model for non-monotonic dose dependence of thermoluminescence (TL). J. Phys. Condens. Matter 17, 737–753], who explained a signal drop in TL by an enhanced recombination rate with electrons at the recombination centre. Finally, an alternative model for the signal decay is given, based on the competition between single and double electron capture at the electron trapping site. From the critical discussion of the different models it is concluded that the double electron capture mechanism is the most probable effect for the dose response. 相似文献
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12.
V. K. Mathur A. C. Lewandowski N. A. Guardala J. L. Price 《Radiation measurements》1999,30(6):735-738
Thermoluminescence dosimetry has been very successful in monitoring the personnel level doses due to high sensitivity and reusability. However, these dosimeters saturate at high doses involved in radiation processing. Present investigations show that the range of high dose measurements can be increased by an order of magnitude by increasing the concentration of dysprosium in CaSO4:Dy. A further increase in high dose measurements is possible by considering the ratio of two high temperature peaks. As the ratio of two peaks is an intrinsic property of the material, it is expected that the initial calibration of these dosimeters may not be required. This may be advantageous at very high doses where calibration of the dosimeters is quite problematic. Use of thermoluminescence peaks higher than 300°C also make this technique appropriate for high dose measurements at high temperatures. 相似文献
13.
Liang Bao Liu Masao Sumita Keizo Miyasaka 《Journal of Macromolecular Science: Physics》2013,52(3-4):309-327
The fatigue behavior of segmented polyurethane and the effect of aging following fatigue were investigated by a combination of thermoluminescence (TL) and pulse NMR. It was found that the peak at 405 K, related to the segmental motion in the interfaces around the hard domains, decreased in intensity in the early stage of fatigue and disappeared at 1.0 × 105 cycles. Meanwhile a new TL peak near 390 K (peak I) appeared and increased in intensity sharply during fatigue up to 1.0 × 105 cycles. In this process the peak at 440 K (peak H) decreased in intensity correspondingly. The maximum temperatures of both peaks remained almost unchanged during fatigue. On the other hand, in the aging process following fatigue, this newly appeared TL peak decreased in intensity and the higher TL peak regained intensity accordingly. The TL and NMR results showed that the enhanced lower TL peak during fatigue is related to a fatigue-induced phase-mixed phase, which has a segmental mobility higher than the interfaces around the hard segment domains, and that this phase-mixed intermediate phase increases in volume fraction as the fatigue proceeds but decreases and is transferred partly to the hard segment domains during aging following fatigue. 相似文献
14.
M.C. Larciprete D. Haertle A. Belardini M. Bertolotti F. Sarto P. Günter 《Applied physics. B, Lasers and optics》2006,82(3):431-437
We measured the second and third order optical nonlinearity of zinc oxide, grown on glass substrates by the ion beam sputtering
technique. Second and third harmonic generation measurements were performed by means of the rotational Maker fringes technique
for different polarization configurations, thus allowing the determination of all non-zero components of the second order
susceptibility at three different fundamental beam wavelengths, i.e., 1064 nm, 1542 nm and 1907 nm. The dispersion of the
nonlinear optical coefficients has been evaluated, while the nonlinear optical coefficients were found to range between 0.9 pm/V
and 0.16 pm/V for d33, 0.53 pm/V and 0.08 pm/V for |d15|, 0.31 and 0.08 pm/V for |d31|, with increasing wavelength. Finally, one third order susceptibility, χijkl
(3), has been determined by third harmonic generation measurements at a fundamental wavelength λ=1907 nm and a value for χ3333
(3) of 185×10-20 m2/V2 has been found.
PACS 42.65.An; 42.65.Ky; 42.70.Nq 相似文献
15.
We elaborate on a recently proposed model of the temporal dependence of polarization mode dispersion in long fiber links. We evaluate the probability that a channel of a wavelength-division multiplexed system never incurs an outage, and the range of frequency over which the parameters that characterize the temporal statistics of the differential group delay are correlated. 相似文献
16.
Part I describes the processes inherent to thermoluminescence phenomena and discusses the information yielded by thermoluminescence measurements on a real crystal. A brief review of the results in alkali halides is presented. In the second part, the method of photostimulated thermoluminescence is presented with a summary of the typical results obtained by the authors: a sample is previously X-rayed at a high temperature; next trap filling is obtained by illumination with monochromatic light; the sample is then heated and the glow curve recorded. The process bears some analogy to photoconductivity, with higher sensitivity; moreover it allows the separation of the electron from the hole contribution and evidences different mechanisms of trap filling. In the last part a recent development of the method is shown, namely the study of photostimulated thermoluminescence in additively colored alkali halide crystals. 相似文献
17.
U.V. excited thermoluminescence of ten textile fibres is investigated above liquid N2 temperature. The results seem to indicate that the glow peak peculiarities are mainly due to structural defects or chemical impurities. The kinetic order of the process is always found to be 1. 相似文献
18.
Measurements were performed on the thermoluminescence build-up of phenanthrene crystals UV excited at liquid N2 temperature. Kinetic investigations show that the passage of electrons from excited molecules to traps takes place by means of a direct process, without the intervention of the conduction band states. Arguments are advanced to point out the possible role of Frenkel excitons in this process. 相似文献
19.
《Radiation measurements》2007,42(4-5):735-738
The genetic algorithm (GA) for simulation of the thermoluminescence (TL) mechanisms in solids was adapted. The realization of main evolutionary operators (selection, crossover and mutation) was carried out with using parameters of the known band schemes. The efficiency of the GA simulation was estimated taking non-interactive multitrap model as an example. 相似文献
20.
The analysis of the kinetics of the thermoluminescence process is faced with a new method. It allows us to verify whether the forms of the kinetic equations are really suitable to represent the shape of the observed glow peaks. Formulae are obtained to get values of activation energy, frequency factor and other concerned parameters. Application is made to the thermoluminescence of ZnS and NaBr showing the reliability of the method. 相似文献