• Journal of Radiation Protection and Research
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• 제43권4호
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• pp.160-169
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• 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.

• 분석과학
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• 제11권5호
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• pp.386-393
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• 1998

란탄이온의 특성 발광선 세기가 TLC plate상에서 증폭되는 현상을 이용하여 $Dy^{3+}$ 이온에 대한 고감도의 미량분석법에 대하여 연구하였다. 수용액 상태에서의 $Dy^{3+}$ 이온의 발광선의 세기에 비하여 주어진 용액 시료를 TLC plate에 점적하면 이온의 방출선의 세기가 크게 증가하였다. 특히 점적된 이온에 o-Phenanthroline을 추가로 점적하면 방출선의 세기가 더욱 증가하는 증폭현상을 이용하여 $Dy^{3+}$ 이온의 검출한계를 용액 시료에 비하여 농도비로 약 10배 그리고 그 절대량으로는 $10^4$배 정도 개선하였으며 이때의 검정곡선은 검출한계 근처에서 $10^2$ order의 선형범위(dynamic range)와 상관계수가 0.99 이상인 직선성을 나타냈다. 한편 이러한 발광증폭의 이론적인 배경으로 착물내의 리간드와 란탄이온 사이의 energy-transfer mechanism을 설명하였다.

• 대한화학회지
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• 제46권6호
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• pp.502-508
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• 2002

본 실험은 N-Carbamoylglycine의 농도 결정에 PET sensor를 응용한 것이다.N-Carbamoylglycine이 금속 이온에 리간드로 작용하면서 착물을 만들고 있는 fluorophore의 luminescence intensity를 변화시킬수 있고 이를 통해 농도결정에 이용할 수 있다. 사용한 금속이 온은 $Ni^{2+}$, $Cu^{2+}$ 그리고 $Zn^{2+}$이며 비교대상으로 아세트산을 사용하여 선택성을 확인하였다. $Ni^{2+}$ 이온은 음이온 리간드에 의해서 eT mechanism 변화를 보여주었으며 , $Cu^{2+}$이온은 아세트산과 N-Carbamoylglycine을 구별하는 선택성을 가지고 있으며, $Zn^{2+}$이온은 매우 예민한 luminscence intensity 변화를 일으키는 것으로 나타났다.

• 소성∙가공
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• 제21권4호
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• pp.246-251
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• 2012

The mechanism for mechano-luminescence(ML) in SAO phosphor was investigated quantitatively by measuring the emission intensity under three different tensile conditions. It was found that the ML of SAO was strongly dependent on the dynamic loading rate rather than by the applied load itself. The mechano-luminescent emission in SAO was evaluated based on the trap-releasing process. It was found that the shape of the ML curve in the transient regime obtained from the rate equation has good agreement with the experimental data.

• Journal of Microbiology and Biotechnology
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• 제4권3호
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• pp.176-182
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• 1994

The light-organ symbiont of pine cone fish, Vibrio fischeri, senses its presence in the host and responds to environmental changes by differentially expressing its symbiosis-related luminescence genes. The V. fischeri luminescence genes are activated by LuxR protein in the presence of an autoinducer. In an effort to elucidate the mechanism of regulation of luxR, a plasmid containing luxR was mutagenized in vitro with hydroxylamine and a luxR mutant plasmid was isolated by its ability to activate luminescence genes cloned in E. coli in the absence of the autoinducer. The specific base change identified by DNA sequencing was only single base transition at ＋78 from the transcriptional start of luxR. Based on a Western immunoblot analysis, the nucleotide change directed the synthesis of much higher level of LuxR protein without any amino acid substitutions. The results suggest that the region including the ＋78th base is presumably internal operator required for autorepression of luxR, and the increased cellular level of LuxR results in activation of luminescence genes by autoinducer independent fashion.

• 한국전기전자재료학회논문지
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• 제14권1호
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• pp.48-53
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• 2001

The crystal structure of ZnS fabricated by gas-liquid phase reaction was refined by the Rietveld program using X-ray diffraction data. The R-weighted pattern (R$\sub$wp/) of ZnS powder was 10.85%. The fraction of HCP phase was closely related with extra amount of H$_2$S gas. The lattice parameters and crystalline size were changed by the relative ratio of multi-phase. The luminescence property of ZnS:Cu, Al green phosphors prepared by conventional methods was good in the range of 91∼94% and 150∼190${\AA}$, respectively. According to the maximum entropy electron density(MEED) methods, any defects in (001) plane of cubic phase were not found. We suggest that both the Rietveld and maximum entropy density methods may be useful tools for studying luminescence mechanism of other phosphors materials.

• International Journal of Precision Engineering and Manufacturing
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• 제7권2호
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• pp.52-55
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• 2006

The OLEDs(Organic Light-Emitting Diodes) structure organizes the bottom layer using glass, ITO(indium thin oxide), hole injection layer, hole transport layer, emitting material layer, electron transport layer, electron injection layer and cathode using metal. OLED has various advantages. OLEDs research has been divided into structural side and emitting material side. The amount of emitting light and luminescence efficiency has been improved by continuing effort for emitting material layer. The emitting light mechanism of OLEDs consists of electrons and holes injected from cathode and anode recombination in emitting material layer. The mobilities of injected electrons and holes are different. The mobility of holes is faster than that of electrons. In order to get high luminescence efficiency by recombine electrons and holes, the balance of their mobility must be set. The more complex thin film structure of OLED becomes, the more understanding about physical phenomenon in each interface is needed. This paper observed what the thickness change of hole transport layer has an affection through the below experiments. Moreover, this paper uses numerical analysis about carrier transport layer thickness change on the basis of these experimental results that agree with simulation results.

• 대한화학회지
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• 제39권9호
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• pp.705-714
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• 1995

란탄이온의 특성 발광선 세기가 Nylon Membrane상에서 증폭되는 현상을 이용하여 $Eu^{+3}$과 $Tb^{+3}$이온에 대한 고감도의 미량분석법에 대하여 연구아였다. 수용액(혹은 에탄올 용액) 상태에서의 $Eu^{+3}$과 $Tb^{+3}$두이온의 발광선의 세기에 비하여 주어진 용액 시료를 Nylon Membrane에 점적하면 이온의 방출선의 세기가 매우증가하였으며 특히 점적된 이온에 o-phenanthroline을 추가로 점적하면 방출선의 세기가 더욱 증가하는 증폭현상을 이용하여 $Eu6{+3}$과 $Tb^{+3}$이온의 검출한계를 용액 시료에 비하여 $10_7$배 이상 개선하였으며 이때의 검정곡선은 검출한계 근처에서 2-3 order의 선형범위(dynamic range)와 상관계수가 0.99 이상인 직선성을 나타냈으며 또한 TLC 방법에 비하여 10배정도의 검출한계 개선효과를 얻었다. 한편 o-phenanthroline의 변화에 따른 선세기의 변화를 관찰한 결과 -4몰비 정도에 최대의 선세기를 보였으며 그 이상에서는 일정한 선세기를 나타내었는데 이런한 발광증폭의 이론적인 배경으로 착물내의 리간드와 란탄이온 사이의 energytransfer mechanism을 설명하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.29-32
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• 2001

Hydrogen passivation of Si nanocrystals identifies luminescence mechanism indirectly. Si nanocrystallites thin films on p-type (100) Si substrate have been fabricated by pulsed laser deposition technique using a Nd:YAG laser After deposition, Si nanocrystallites thin films have been annealed at 600$^{\circ}C$ and 760$^{\circ}C$ in nitrogen ambient, respectively. Hydrogen passivation was subsequently performed at 500$^{\circ}C$ in forming gas (95 % N$_2$ + 5 % H$_2$) for an 1 hour. We report the photoluminescnece(PL) property of Si thin films by the hydrogen passivation. The luminescence mechanism of Si nanocrystallites has also been investigated.

• Journal of Korean Vacuum Science & Technology
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• 제6권2호
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• pp.58-61
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• 2002

Photoluminescence up-conversion in semiconductor heterostructures is a phenomenon in which luminescence occurs at energies higher than that of the excitation photons. It has been observed in many semiconductor heterostructure systems, including InP/AnALAs, CdTe/CdMgTe, GaAs/ordered-(Al)GalnP, GaAs/AIGaAs, and InAs/GaAs. In this wort, GaAs/AIGaAs heterostructures are used as a model system to study the mechanism of the up-conversion process. This system is ideal for testing different models because the band offsets are quite well documented. Different heterostructures are designed to study the effect of disorder on the up-converted luminescence efficiency. In order to study the roles of different types of carriers, the effect of doping was investigated. It was found that the up-converted luminescence is significantly enhanced by p-type doping of the higher-band-gap material.