• Advances in nano research
• /
• v.1 no.4
• /
• pp.193-202
• /
• 2013

In this article, we present the effects of Ag doping and after-growth thermal annealing on the photoluminescence (PL) and thermoluminescence (TL) behaviors of $SnO_2$ nanoparticles. $SnO_2$ nanoparticles of 4-7 nm size range containing different Ag contents were synthesized by hydrothermal process. It has been observed that the after-growth thermal annealing process enhances the crystallite size and stabilizes the TL emissions of $SnO_2$ nanostructures. Incorporated Ag probably occupies the interstitial sites of the $SnO_2$ lattice, affecting drastically their emission behaviors on thermal annealing. Both the TL response and dose-linearity of the $SnO_2$ nanoparticles improve on 1.0% Ag doping, and subsequent thermal annealing. However, a higher Ag content causes the formation of Ag clusters, reducing both the TL and PL responses of the nanoparticles.

• Preventive Nutrition and Food Science
• /
• v.7 no.2
• /
• pp.188-194
• /
• 2002

This study was carried out to observe changes in several detection factors derived from thermoluminescence (TL) of minerals separated from irradiated Korean perilla and sesame seeds during storage under normal room and darkroom conditions. The TL intensities of the first glow curves increased from 0 to 5 kGy but only slightly increase from 5 to 10 kGy. Maximum TL temperatures of the first glow curves in all irradiated samples were around 20$0^{\circ}C$, ranging from 150 to 25$0^{\circ}C$. Since the control (0 day of storage) glow curve ratios of G3 and G4, calculated from re-irradiated (1 kGy) sample were over 0.5, detection of irradiation was possible. However, because Gl ratios were below 0.1, they were classified as non-irradiated. There was n unique first glow curve shape that could be clearly seen in all irradiated samples, regardless of storage conditions, that was never seen in non-irradiated samples. In all samples, the maximum TL temperatures and shape of the second glow curve was in a lower temperature range than that of the first glow curve. Therefore, detection of irradiated Korean perilla and sesame seeds was possible fur up to 3 months after irradiation, regardless of storage conditions, by examining several TL detection factors; including TL intensity, glow curve ratios maximum TL temperatures, and the shapes of glow curves.

• Preventive Nutrition and Food Science
• /
• v.3 no.1
• /
• pp.22-26
• /
• 1998

Model food containing common salt(NaCl) was subjected to the thermoluminescene(TL) detection whether it is irradiated or not. Salt irradiated with $^60Co$-gamma ray and electron beam exhibited a characteristic TL gowcurve depending on the irradiation dose, showing major peaks at $206^{\circ}C$ and $326^{\circ}C$. The intensity of TL glowcurves was directly proportional to the irradiated doses regardless of irradiation sources at each concentration of salt. A high correlation coefficient was observed for irradiated salt between the irradiation doses and the corresponding TL responses. At the same dose, the intensity of TL glowcurve increased as the concentration of salt increased in the test sample. TL glowcurves of nonirradiated salt and irradiated model food without salt were negligible and similar to a baseline . However, irradiated model food containing salt gave rise to a characteristic TL glowcurve with two major peaks at about $240^{\circ}C$ and $300^{\circ}C$, respectively. The results showed that salt played a role as an internla as well as external indicator in TL measurements, indicating that TL will be applicable to other condiments and spices with salt for their detection whether they are irradiated or not.

• Analytical Science and Technology
• /
• v.12 no.6
• /
• pp.558-564
• /
• 1999

A method for measuring archaeological dose of Packjae pottery shards using thermoluminescence dosimetry(TLD) has been studied. TL measurement has been achieved using quartz crystals in the size range of 90 to $125{\mu}m$ diameter extracted from the pottery shards. The stable temperature region of the TL glow curve which is devoid of anomalous fading components was identified by the plateau test and found to exist from 265 to $300^{\circ}C$. The archaeological dose of the pottery shards was estimated to be 7.43 Gy using the dose calibration curves obtained from sequential irradiation of $^{137}Cs$ gamma source to the samples and TL measurement of natural samples.

• Food Science and Biotechnology
• /
• v.18 no.2
• /
• pp.374-378
• /
• 2009

Three physical methods, photostimulated luminescence (PSL), thermoluminescence (TL), and electron spin resonance (ESR), have been applied to detect the irradiation treatment for the non- and steamed sesame seed samples. PSL successfully screened the irradiated samples from the non-irradiated control by comparing their photon counts (PCs) with the lower (less than 700 count/60 sec) and upper threshold values (higher than 5,000 count/60 sec). TL signals were still detected in all irradiated samples even after steaming, which was reconfirmed with TL ratios [integrated area of $TL_1$ (the first glow)/$TL_2$ (the second glow)] through re-irradiation step. ESR spectrometry showed that radiation-induced cellulose radicals were detected in all the irradiated samples irrespective of steaming treatment. Identification of the irradiated sesame seeds was possible even after steaming by analyzing PSL, TL, and ESR.

• Food Science and Preservation
• /
• v.13 no.1
• /
• pp.50-54
• /
• 2006

The identification characteristics of inadiated dried onion and garlic at 1, 4 and 7 kGy were investigated by analyzing their photostimulated luminescence (PSL), thermoluminescence (TL) and electron spin resonance (ESR). The PSL results showed that the photon counts of non-irradiated dried onion were less than 700 (negative) and those of irradiated samples at 1kGy or more were over 5000 (positive), making it possible to discriminate non-irradiated onions from irradiated ones. However, the intermediate counts (700-5000) were observed in irradiated garlic at 1 and 4 kGy, even though positive counts were measured in 7 kGy group. Radiation-induced TL glow curves $(TL_1)$ were measured at $150^{\circ}C$ range in both irradiated onion and garlic samples at 1 kGy or more, which could identify irradiated groups. Furthermore, determination of TL ratios $(TL_1/TL_2)$ for both samples could verify the above results. It was found, however, that ESR spectroscopy was not suitable for the detection of irradiated dried onion and garlic.

• Journal of Radiation Protection and Research
• /
• v.43 no.4
• /
• pp.160-169
• /
• 2018

Background: This study aims to develop an integrated optical system that can simultaneously or selectively measure the signals obtained from radioluminescence (RL), thermoluminescence (TL), and optically stimulated luminescence (OSL), which are luminescence phenomena of materials stimulated by radioactivity, heat, and light, respectively. The luminescence mechanism of various materials could be investigated using the glow curves of the luminescence materials. Materials and Methods: RL/TL/OSL integrated measuring system was equipped with a X-ray tube (50 kV, $200{\mu}A$) as an ionizing radiation source to irradiate the sample. The sample substrate was used as a heating source and was also designed to optically stimulate the sample material using various light sources, such as high luminous blue light emitting diode (LED) or laser. The system measured the luminescence intensity versus the amount of irradiation/stimulation on the sample for the purpose of measuring RL, TL and OSL sequentially or by selectively combining them. Optical filters were combined to minimize the interference of the stimulation light in the OSL signal. A long-pass filter (420 nm) was used for 470 nm LED, an ultraviolet-pass filter (260-390 nm) was used for detecting the luminescence of the sample by PM tube. Results and Discussion: The reliability of the system was evaluated using the RL/OSL characteristics of $Al_2O_3:C$ and the RL/TL characteristics of LiF:Mg,Cu,Si, which were used as dosimetry materials. The RL/OSL characteristics of $Al_2O_3:C$ showed relatively linear dose-response characteristics. The glow curve of LiF:Mg,Cu,Si also showed typical RL/OSL characteristics. Conclusion: The reliability of the proposed system was verified by sequentially measuring the RL characteristics of radiation as well as the TL and OSL characteristics by concurrent thermal and optical stimulations. In this study, we developed an integrated measurement system that measures the glow curves of RL/TL/OSL using universal USB-DAQs and the control program.

• Korean Journal of Food Science and Technology
• /
• v.30 no.3
• /
• pp.509-516
• /
• 1998

Thermoluminescence measurements were applied to the detection of seasoned-powered foods such as shellfish extract powder, seasoned marine products, Ramen soup powder and sardine extract powder whether they are irradiated or not. Correlation coefficients $(R^2)$ between irradiation doses and corresponding TL responses were more than 0.5966 in all samples and 0.9500 in Ramen soup powder. TL threshold value was pre-established for the detection of unknown Ramen soup powders by verifying TL responses with a re-irradiation step. Threshold values were maximum 1.37 for the nonirradiated samples and minimum 6.06 for the 2.5 kGy-irradiated samples. The samples showing values between 1.37 and 6.06 were subjected to a re-irradiation step for their detection, which results were reconfirmed by enumerating the total bacterial load of the detected samples. Pre-established threshold values were successfully applicable to the detection of 167 coded unknown samples, both nonirradiated and irradiated with gamma or electron-beam energy. In the assessment of irradiated doses, three calibration curves were pre-established by plotting TL intensity versus applied doses, of which a quadratic equation was obtained for the potential estimation of irradiated doses with some variations from the real doses.

• Korean Journal of Materials Research
• /
• v.12 no.11
• /
• pp.870-874
• /
• 2002

$Mg_2$$SiO_4$: Dy, Tb pellets were made by using a sintering process, including pressing and heat treatment. In the present study, the optimum parameters of the sintering for the $Mg_2$$SiO_4$: Dy, Tb pellets obtained such as the pressing pressure, the sintering temperature and the sintering time were in terms of thermoluminescence. Experimental results showed that the main peak of the glow curve for $Mg_2$$SiO_4$: Dy, Tb thermoluminescence dosimeter was clearly correlated with the energy of the UV and with the grain size. The intensity of the TL glow curve increased and its main peak position shifted to lower temperature with increasing UV irradiation time.

• Nuclear Engineering and Technology
• /
• v.2 no.4
• /
• pp.269-272
• /
• 1970

Thermoluminescence (TL) from LiF powder of purity 99.98 ％ was accomplished and this TL intensity showed glow peaks at 12$0^{\circ}C$, 22$0^{\circ}C$ and 30$0^{\circ}C$. Sintered LiF powder which has an activation of 2％ proportion by weight of MgC1$_2$show strong increased TL and this characteristic of the glow curve was investigated precisely. LiF which is used in TL dosimetry has been known to have electrons caused by impurities such as Mg, Mn, etc. This experiment shows that Mg, one of the impurities, is definitely diffused through LiF crystals. The effects of sintering time were detected in this glow curve and it was confirmed that MgC1$_2$also has a TL effect.