Thermoluminescence governed by the Auger-recombination process

We suggest a model of the atomic and electronic processes responsible for the so-called 110 and 325 °C thermoluminescence (TL) peaks, including predose behavior, and for the room temperature optically stimulated luminescence (OSL) of quartz. Our model is based on defects and defect processes typical of those known from many previous studies of quartz. It explains the experimental observations that the two TL peaks and OSL are correlated with respect to the effects of thermal annealing and photoexcitation after irradiation. The model indicates that the energy for the two TL peaks and OSL is all stored by the same defect pairs. These defect pairs comprise [AlO4]− and [X/M+]+ generated by a radiolytic reaction [AlO4/M+]0→[AlO4]−+M+. Here [AlO4]− is an Al impurity center substituting a Si atom, M+ is an alkali ion, [X/M+] is M+ stabilized by a defect denoted by X and [AlO4/M+]0 is an [AlO4]− center charge compensated by M+. Even though the 110 and 325 °C TL peaks and OSL arise from the same defect pairs, they should emit different luminescence because they arise through different mechanisms: the 325 °C TL peak through the migration of M+, and the OSL through the migration of holes. The 110 °C TL peak is ascribed to the electron–hole recombination at the [AlO4]− centers. According to the model, the TL at 110 and 325 °C and OSL luminesce at different wavelengths.

Thermoluminescence dating of calcite – Alpha effectiveness and measurement protocols

Surface trapping and Auger recombination typically suppress the emission of quantum dots (QDs). Understanding how these two processes affect the emission properties of QDs is critical to optimizing their photoluminescence (PL) performance. However, isolating their respective contributions can be challenging. In this study, we investigate the respective effects of surface trapping and Auger recombination on QD emission using single QD spectroscopy. The effects of surface trapping and Auger recombination on QD emission can be distinguished by analyzing the real-time changes in the radiative and non-radiative rates of the PL trajectories of single QDs. This is because Auger recombination can alter both the radiative and non-radiative rates, while surface trapping changes only the non-radiative rate. We find that when the PL trajectory of a single QD is in a gray state due to surface trapping, it can still exhibit Auger blinking induced by charging. Surface trapping introduces non-radiative recombination pathways not only for neutral exciton states but also for trion states. This further confirms that surface trapping and Auger recombination in QDs are completely independent non-radiative pathways. The ability to distinguish the respective effects of Auger recombination and surface trapping provides valuable insights into QD emission mechanisms.

Electron beam induced thermoluminescence from Li + implanted Al 2O 3

Investigation of emission spectra, dose response and stability of luminescence from NaCl

Equivalent dose estimation of calcite using isothermal thermoluminescence signals

Determination of trapping parameters of the high temperature thermoluminescence peak in equilibrated ordinary chondrites

Effect of optical bleaching on the dosimetric TL peak in Al2O3:C for blue and UV emissions

The thermoluminescence (TL) of polycarbonate doped with triphenyl methane and xanthene dyes was measured following irradiation with ultraviolet light at 77 K and the effect exercised by systematically varying excitation wavelength, irradiation dose, and dopant concentration were investigated. The TL glow curves are characterized by two distinct peaks that can be attributed to genuine emissions of the dopant‐polymer systems and involve continuous distributions of apparent activation energies as determined by partial heating techniques. The low‐temperature peak extends over the temperature interval corresponding approximately to the complex β relaxation of the polymeric units (short‐range chain motions), but no obvious correlation between the two phenomena can be evidenced because the TL peak is never structured and the values and type of evolution of apparent activation energies as a function of temperature are clearly different from those observed for the β relaxation. In this temperature range the TL properties are consistent with an ionization of the dye followed by a recombination process involving electron tunneling from trap to luminescence center rather than thermal excitation. The second TL peak appears in a unusually high temperature region (> 250 K) where no intrinsic relaxation of the polymeric matrix is known to occur. This is not to say that the chain motions cannot contribute to some extent to the detrapping processes. Generally speaking, however, the TL results show that interpreting glow curves only in terms of relaxation processes should be done with great caution and that in certain cases an observed emission must be considered as specific to the dopant‐polymer system rather than to the polymer itself.

An investigation of the relationship between the 110°C TL peak and optically stimulated luminescence in sedimentary quartz

Testing a model-guided approach to the development of new thermoluminescent materials using YAG:Ln produced by solution combustion synthesis

The Yanzhuang meteorite is a heavily shocked chondrite and composed of light-colored unmelted phase and black-colored melted phase. Our thermoluminescence (TL) determinations have revealed that the intensities of natural TL for its unmelted phase and melted phase are different. The equivalent β-dose of unmelted phase is in about three times higher than that of melted phase, indicating the temperature of melted phase is much higher than that of unmelted phase. Two special TL phenomena have been found in Yanzhuang meteorite through the determination of the natural TL, annealed TL, and induced TL by β-radiation: (1) When the sample of Yanzhuang meteorite is annealed at temperature up to 500 °C, the TL peak induced by β-rays moves to lower temperature with the increasing of irradiation dose; (2) when the annealed temperature is greater than 600 °C, the TL peak temperature of the annealed sample is higher than that of the unannealed sample, indicating the shock effect changes the TL characteristics of the chondrite. The measured equivalent β-dose for the Yanzhuang unmelted and melted phases are 9238 Gy and 2753 Gy, respectively, showing that the thermal event age for the two parts in this meteorite is not equal, and their thermal histories are not the same, either.

TL, OSL and ESR studies on beryllium oxide

Lithium tetraborate (LBO or LTO) single crystal seems to be a promising new material for thermoluminescent dosimeter (TLD) and SAW resonators. In the present work, thermoluminescence (TL) characteristic and TL spectra of LTO single crystal grown by Bridgman method were measured, the kinetic parameters of TL traps were calculated, and TL spectra were analyzed. The result shows: The primary glow peaks are at about 186oC and 313oC. The activation energies of the traps corresponding to the two TL peaks are 0.96eV and 1.56eV, and the frequency factors are about 7.94×109s-1 and 6.31×1012s-1. The TL spectra of LTO crystal extends from 350nm to 460nm, and has its maximum at about 381nm. The intrinsic luminescent centers can send the energy from crystal lattice to Cu+ ions, because the activation energies of two are quite similar, and the Cu+ ions become new luminescent centers to increase TL sensitivity when Cu ions are doped into LTO crystals.

Mechanisms are inherently constrained devices. Combining flexibility with mechanisms usually requires using Lagrange multipliers to handle the constraints. The added algebraic or numerical tedium, associated with the Lagrange multipliers, is well documented. Presented in this paper is a technique for obtaining the minimal set of hybrid parameter differential equations for a constrained device. That is, the set of equations that inherently incorporate the constraints. The technique illustrated in this paper is a recently developed hybrid parameter multiple body (HPMB) system modeling methodology. The variational nature of the methodology allows rigorous equation formulation providing not only the complete nonlinear, hybrid differential equations, but also the boundary conditions. The methodology is formulated in the constraint-free subspace of the system’s configuration space, thus Lagrange multipliers are not needed for constrained systems, regardless of the constraint type (holonomic or nonholonomic). To evince the utility of the method, a flexible four bar mechanism is modeled. Particularly, the inversion of the slider crank found in the quick return mechanism. A comparison of Hamilton’s principle and the described technique, as they are applied to the mechanism, is included. It is shown that the same equations result from either method, but the new technique is much more concise, more efficiently handles the constraints, and requires less algebraic tedium.