Search results for "THERMOLUMINESCENCE"
showing 10 items of 85 documents
Luminescence properties of LiGaO2 crystal
2017
The study was supported by the Latvia-Lithuania-Taiwan research project “Nonpolar ZnO thin films: growth-related structural and optical properties” (Latvia: LV-LT-TW/2016/5 , Lithuania: TAP LLT 02/2014 , Taiwan: MOST 103-2923-M-110-001-MY3 ).
Influence of boron on donor–acceptor pair recombination in type IIa HPHT diamonds
2013
Abstract We report on the investigation of donor–acceptor pair (DAP) and free carrier recombination in HPHT IIa type diamonds and determination of boron concentration by differential transmittivity (DT) technique. Photoluminescence and photoluminescence excitation spectra were measured in 8–300 K temperature range and provided a broad (~ 0.67 eV) Gaussian DAP band which peaked at 2.2 eV at low temperatures, while above 200 K it sharply shifted to 2.5 eV and became more intense. Thermoluminescence measurements also demonstrated a similar tendency. This peculiarity was explained by DAP recombination between the nitrogen and the boron, the latter being in the ground and the excited states at l…
Luminescence of fluorine doped silica glass
2003
Abstract The role of fluorine doping on silica properties was studied by luminescence methods. Non-doped samples of the same preparation technology possess an absorption band at 7.6 eV on the level of 2 cm−1. A trace of this band in the fluorine-doped sample is on the level of 0.1 cm−1. In both samples 7.6 eV photons as well as ionizing irradiation (X-ray, electron beam) excite photoluminescence of so-called oxygen deficient centers with a blue (2.7 eV) and a UV band (4.4 eV). The luminescence of the fluorine doped sample increases with dose many times from the initial low level for the same excitation. Also, thermally stimulated luminescence appears after irradiation. The energetic yield u…
Anomalous behavior of LiF:Mg,Cu,P (TLD100H) irradiated with electron beams
2006
Abstract Thermoluminescent dosimeters of LiF:Mg,Cu,P (TLD100H) were exposed to 60Co γ -ray, protons, high energy electrons and the glow curves were analyzed. We observed an unusual behavior of the TL response of dosimeters to 7 and 14 MeV electron beam. In fact the relative amplitude between two of the five peaks (2° and 3° peaks) assumes values smaller than the unity for doses up to 5 Gy and values greater than the unity for doses equal to or greater than 10 Gy. A possible explanation of this behavior is given adopting a model of the formation of the peaks 2° and 3° and examining the different ways of energy release in matter for each beam. To perform this analysis we deconvoluted the glow…
Glow curve analysis of TLD-100H irradiated with radiation of different LET: Comparison between two theoretical method
2006
In the present paper we show the result of study on the thermoluminescent signal of LiF:Mg,Cu,P (TLD-100H) after irradiation with beams of different LET (photons, electrons and protons). Through the analysis of the glow curve it is possible to obtain information on the LET of the radiation beam. To perform this analysis we have deconvoluted the glow curves adopting general order kinetic equation for the description of the peak shape. In addition a numerical simulation has been performed to find a connection among the physical parameters of the model (OTOR) and the parameters of the empirical expression used in the analysis of the experimental data (GOK). The methodology indicate that the ki…
Discrimination of LINAC photon and sunlight contributions in watch glass analyzed by means of thermoluminescence
2012
Abstract The research described in this paper shows how to extract from the glow curves of watch glasses exposed to LINAC photons and sunlight a contribution sensitive to LINAC photons dose. As first step, the dependence of the TL signal due to sunlight on the exposure duration was studied and a signal saturation was observed after about 20 weeks. The comparison of TL signals due to solar light and to LINAC photons highlights a partial overlap of the two signals. Here, two different analysis procedures of glow curves (general order kinetics deconvolution and principal components analysis) are reported to point out components which depend differently on LINAC photon radiation dose. For both …
Radiation processes in oxygen-deficient silica glasses: Is ODC(I) a precursor of E′-center?
2006
Abstract The accumulation of radiation-induced defects under non-destructive X-ray and destructive cathodoexcitation was studied in pure silica KS-4V glasses possessing an absorption band at 7.6 eV. The correspondence between the existence of this band and the creation of the E′-center by radiation was checked. Detection of induced defects was accomplished by measurement of the luminescence during irradiation, post irradiation afterglow or phosphorescence, induced optical absorption, and thermally stimulated luminescence. In all samples, these observed phenomena associated with charge trapping and recombination on the oxygen-deficient luminescence center. Others centers of luminescence were…
UV-light induced luminescence processes in Al2O3 bulk and nanosize powders
2010
Abstract UV-light induced photoluminescence (PL) and thermoluminescence (TL) have been studied in the alumina (Al2O3) bulk and nanosize powders. It has been found that luminescence properties of the studied alumina powders are determined mainly by presence of the uncontrolled impurities of titanium, iron and chromium. Despite the general similarity of PL characterized by two main emission band around 400 and 750 nm a number of differences has been observed in relative yield and position of the emission bands as well as in the excitation spectrum of the short wavelength band. Essential differences have been observed also in the intensity of the TL signal, TL curves and TL emission spectra re…
Particle size-related limitations of persistent phosphors based on the doped Y3Al2Ga3O12 system
2021
AbstractCo-doped Ce3+, Cr3+ and Pr3+ yttrium–aluminium–gallium garnet powders of various sizes were obtained by co-precipitation method. The microstructure and morphology were investigated by XRPD, TEM and gas porosimetry. The luminescence properties were studied by excitation and emission spectra, quantum yield and decay times. Thermoluminescence measurements were performed to evaluate the activation energy, traps redistribution and frequency factor. Limitation in the energy transfer between dopant ions in the small particles, traps depth and surface defects were considered and investigated as responsible for the quenching of persistent luminescence. The phosphors annealed at 1100 °C show …
Thermostimulated recombination processes in LiBaF3 crystals
2004
Abstract The creation of radiation defects in LiBaF 3 crystals at 10 K and the processes of their thermostimulated recombination are investigated. The methods of optical absorption, thermal bleaching of color centers, thermostimulated luminescence and fractional glow technique are used. The radiation defects anneal in a multi-stage process accompanied with thermo-luminescence at 20, 46, 105, 130, 170, 210 and 270 K . Differences in the optical absorption spectra measured before and after the TSL peaks are obtained and recombination parameters are determined. The TSL peak at 20 K arises from the delocalization of H-centers. The presence of two TSL peaks related to V K -centers at 105 and 130…