• Bulletin of the Korean Chemical Society
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• v.24 no.9
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• pp.1396-1398
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• 2003

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.4
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• pp.497-508
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• 2020

In the geochemical field, the chemical speciation of hexavalent uranium (U(VI)) has been widely investigated by performing measurements to determine its luminescence properties, namely the excitation, emission, and lifetime. Of these properties, the excitation has been relatively overlooked in most time-resolved laser fluorescence spectroscopy (TRLFS) studies. In this study, TRLFS and continuous-wave excitation-emission matrix spectroscopy are adopted to characterize the excitation properties of U(VI) surface species that interact with amorphous silica. The luminescence spectra of U(VI) measured from a silica suspension and silica sediment showed very similar spectral shapes with similar lifetime values. In contrast, the excitation spectra of U(VI) measured from these samples were significantly different. The results show that distinctive excitation maxima appeared at approximately 220 and 280 nm for the silica suspension and silica sediment, respectively.

• Analytical Science and Technology
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• v.31 no.1
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• pp.7-13
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• 2018

In this study, we measured the time-resolved optically stimulated luminescence (TR-OSL) of Paleolithic paleosol quartz and evaluated its lifetime. Considering the lifetime dependence on the preheating applied after irradiation, the radiation exposure, and the optical pulse stimulation, we found that the optimum measurement condition for determining the lifetime of paleosol quartz was the optical pulse stimulation at a dwelling time of $250{\mu}s$, pulse width of $10{\mu}s$, and sweep number of 100,000, without preheating after 100 Gy of irradiation. Based on the dependence of the lifetime on the reading temperature, the thermal quenching activation energy ${\Delta}E$ and thermal assistance activation energy $E_a$ were evaluated as $0.60{\pm}0.14eV$ and $0.053{\pm}0.029eV$, respectively. These values were in good agreement with those reported in the literature. Therefore, we concluded that the resulting kinetic parameters for paleosol quartz are quite reliable.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2000.11a
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• pp.129-132
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• 2000

Perdeuterated hexaflouroacetyIacetonato-ytterbium $[Yb(HFA-D)_3]$ complexes were synthesized by the keto-en01 tautomerism reaction of $Yb(HFA-D)_3$ in methanol-$d_4$ in order to reduce the radiationless transition to the ligands. The luminescence properties of $Yb(HFA-D)_3$ complex were measured in the following anhydrous deuterated organic solvents ; Acetone-$d_6$, Methanol -$d_4$, THF-$d_6$, PO$(OHC_3)_3$ and DMSO-$d_6$. The intensity, lifetime and quantum efficiency of the luminescence in DMSO-$d_6$ were superior to those in other deuterated solvents. It was suggested that the anhydrous DMSO-$d_6$ might be the most appropriate solvent for the liquid laser material of $Yb(HFA-D)_3$ complex.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.15-18
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• 2001

Perdeuterated hexaflouroacetylacetonato-ytterbium [Yb(SOL)-D)$_3$] complexes were synthesized by the keto-enol tautomerism reaction of Yb(SOL-H)$_3$ in methanol-d$_4$in methanol-d$_4$in order to reduce the radiationless transition to the ligands. The luminescence properties of Yb(SOL-D)$_3$complex were measured in the following anhydrous deuterated organic solvents ; Methanol-d$_4$, THF-d$\sub$8/, PO(OCH$_3$)$_3$ and DMSO-d$\sub$6/. The intensity, lifetime and quantum efficiency of the luminescence in DMSO-d$\sub$6/ were superior to those in other deuterated solvents. It was suggested that the anhydrous DMSO-d$\sub$6/ might be the most appropriate solvent for the liquid laser material of Yb(SOL-D)$_3$ complex.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.640-643
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• 2001

Perdeuterated hexaflouroacetylacetonato-ytterbium [Yb(SOL-D)$_3$] complexes were synthesized by the keto-enol tautomerism reaction of Yb(SOL-H)$_3$in methanol-d$_4$in order to reduce the radiationless transition to the ligands. The luminescence properties of Yb(SOL-D)$_3$complex were measured in the following anhydrous deuterated organic solvents ; Methanol-d$_4$, THF-d$_{8}$, PO(O$CH_3$)$_3$and DMSO-d$_{6}$. The intensity, lifetime and quantum efficiency of the luminescence in DMSO-d$_{6}$ were superior to those in other deuterated solvents. It was suggested that the anhydrous DMSO-d$_{6}$ might be the most appropriate solvent for the liquid laser material of Yb(SOL-D)$_3$complex.complex.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.129-132
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• 2000

Perdeuterated hexafluoroacetylacetonato -ytterbium [$Yb (HFA -D)$_3$_3$] complexes were synthesized by the koto-enol tautomerism reaction of $Yb(HFA-H)_3$ in methanol-$d_4$, in order to reduce the radiationless transition to the ligands. The luminescence properties of $Yb(HFA-D)_3$ complex were measured in the following anhydrous deuterated organic solvents : Acetone-$d_6$, Methanol-$d_4$, THF-$d_8$, $PO(OC$H_3$)_3$ and DMSO-$d_6$. The intensity, lifetime and quantum efficiency of the luminescence in DMSO-$d_6$ were superior to those in other deuterated solvents. It was suggested that the anhydrous DMSO-d$_{6}$ might be the most appropriate solvent for the liquid laser material of $Yb(HFA-D)_3$ complex.x.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.11
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• pp.928-933
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• 2001

Perdeuterated hexaflouroacetylacetonato-ytterbium [Yb(SOL-D)$_3$] complexes are synthesized by the keto-enol tautomerism reaction of Yb(SOL-H)$_3$ in methanol-d$_4$ in order to reduce the radiationless transition to the ligands for the high power solid state laser material. The luminescence properties of Yb(SOL-D)$_3$ complex are measured in the following anhydrous deuterated organic solvents ; Methanol-d$_4$, THF-d$_{8}$, PO(O$CH_3$)$_3$ and DMSO-d$_{6}$. The Luminescence intensity, lifetime and quantum efficiency in DMSO-d$_{6}$ are superior to those in other deuterated solvents. It is suggested that the anhydrous DMSO-d$_{6}$ might be the most appropriate solvent for the laser material of Yb(SOL-D)$_3$ complex.complex.

• Korean Journal of Materials Research
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• v.30 no.8
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• pp.413-420
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• 2020

Lu₃Al_5-xGa_xO₁₂:Ce³⁺,Cr³⁺ powders are prepared using a solid-state reaction method. To determine the crystal structure, Rietveld refinement is performed. The results indicate that Ga³⁺ ions preferentially occupied tetrahedral rather than octahedral sites. The lattice constant linearly increases, obeying Vegard's law, despite the strong preference of Ga³⁺ for the tetrahedral sites. Increasing x led to a blue-shift of the Ce³⁺ emission band in the green region and a change in the emission intensity. Persistent luminescence is observed from the powders prepared with x = 2-3, occurring through a trapping and detrapping process between Ce³⁺ and Cr³⁺ ions. The longest persistent luminescence is achieved for x = 2; its lifetime is at least 30 min. The findings are explained using crystal structure refinement, crystal field splitting, optical band gap, and electron trapping mechanism.

• Journal of Radiation Protection and Research
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• v.42 no.1
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• pp.69-76
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• 2017

Background: Time-resolved optically stimulated luminescence (TR-OSL) is a very useful method for calculating the lifetimes of crystalline quartz and feldspar. Materials and Methods: A compact TR-OSL system was developed, comprising a heater assembly manufactured using Kanthal wire, 2 powerful blue light-emitting diodes (LED, LXHL-PB02) for optical stimulation equipped with VIS liquid light guides, and a photomultiplier tube combined with an optical filter for luminescence detection. A pulse generated from the data acquisition board (NI PCI 6250) was used to initiate on/off signals in LED and TR-OSL measurements. Results and Discussion: The TR-OSL and background signals measured using this TR-OSL system using quartz samples were very similar to those reported in a previous study. Additionally, the lifetimes of the build-up and TR-OSL signals were calculated as $27.4{\pm}2.2{\mu}s$ and $30.3{\pm}0.6{\mu}s$, respectively, in good agreement with the findings of a previous study. Conclusion: It was concluded that the developed TR-OSL system was very reliable for TR-OSL signal measurements and lifetime calculations.