• Journal of the Korean Graphic Arts Communication Society
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• v.29 no.1
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• pp.23-33
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• 2011

This experimental focus to characterize luminescence properties related to CNT (Carbon Nano Tube) element dispersedly implanted in ZnS-based phosphor thin film panel fabricated by a screen printing method. More specifically FE-SEM measurements, L-V(Luminescence vs. Voltage) and photo luminescence were carried out to determine an optimum value of CNT concentration and film thickness for the thin film structure of CNT-ZnS:(Cu, Al) by the screen printing method. We confirmed that an optimum value of CNT concentration in the ZnS:(Cu, Al) film panel is about 0.75 wt% resulting that the electric conductivity is 1.6 times higher than that of pure CNT sample and showing that the luminescence intensity is increasing until the optimum concentration. Clearly, CNT is presenting in the luminescence process providing a pathway for the creation of hot electron and a channel for the electron-hole recombination but overly inserted CNT may hinder to produce the hot electron for making an avalanching process. In case of the overly doped CNT 1.0 wt% in the ZnS-based phosphor, the luminescence intensity is decreasing although the electric conductivity is exponentially increasing. Based on these results, we realized that hot electron occurred by the external electric field or exciton arose by the external photon source are reduced dramatically over the critical value of CNT concentration because CNT element provide various isolated residues in the composites of ZnS based phosphor rather than pathway or channel for the D-A(Donnor to Acceptor) pair transition or the radiative recombination of electron-hole.

• Bulletin of the Korean Chemical Society
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• v.31 no.8
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• pp.2151-2157
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• 2010

Spectroscopic and quantum mechanical studies of the Et3PAuCl complex were performed to characterize the effect of aurophilicity on the optical properties. When excited with UV light at low temperature, the crystalline complex produced a deep luminescence in both the blue (high-energy) and red (low-energy) regions of the spectrum. The intensity of the low-energy luminescence was markedly reduced in the powdered state and quenched in the solution state. Time-dependent density functional theory (TD-DFT) calculations on electronic structures of both the ground and excited states of aggregates $[Et_3PAuCl]_n$ (n = 1 - 3) indicated that the low-energy luminescence was attributable to Au-centered transitions, which are significantly affected by aurophilic interactions. By contrast, the high-energy luminescence appeared to be independent of the state of the complex and was strongly associated with the charge transfer from Cl to Au.

• 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.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.170.2-170.2
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• 2015

Enormous interest in trivalent rare-earth (RE) ions activated luminescent materials has been gaining owing to their promising applications in bio-imaging, solar cells, white light-emitting diodes and field-emission displays. Among these trivalent RE ions, dysprosium (Dy3+) was widely investigated due to its unique photoluminescence (PL) emissions. A series of Dy3+-activated CaWO4 phosphors were prepared by a facile high-temperature solid-state reaction method. The X-ray diffraction, PL spectra, cathodoluminescence (CL) spectra as well as PL decay curves were used to characterize the prepared samples. Under ultraviolet light excitation, the characteristic emissions of Dy3+ ions were observed in all the obtained phosphors. Furthermore, the PL emission intensity increased gradually with the increment of Dy3+ ion concentration, reaching its maximum value at an optimized Dy3+ ion concentration. Additionally, color-tunable emissions were obtained in Dy3+-activated CaWO4 system by adjusting the Dy3+ ion concentration and excitation wavelength. Ultimately, strong CL properties were observed in Dy3+-activted CaWO4 phosphors. These results suggested that the Dy3+-activted CaWO4 phosphors may have potential applications in the field of miniature color displays.

• Journal of the Semiconductor & Display Technology
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• v.7 no.4
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• pp.19-22
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• 2008

Thin film has been an increasing important subject of intensive research, owing to the fact that these films possess desirable optical, electrical and electrochemical properties for uses in many semi-conducting nano-crystal applications, such as light-emitting diodes, lasers and solar cell applications. Here, ZnSe thin films were deposited by electrochemical method for the applications of light emitting diode. Electrochemical deposition of ZnSe thin film is not easy, because of the high difference of reduction potential between zinc ion and selenium acid. In order to handle the band gap of ZnSe crystal thin films easily, electrochemical methods are promising to manufacture these films economically. Therefore we have investigated the present study to characterize zinc selenide thin films deposited on ITO glass plates electrochemically. The luminescent properties of ZnSe films have been evaluated by UV-Vis spectrometer and luminescence spectrometer. And the morphology of the film surface has been discussed qualitatively from SEM images.

• Journal of Marine Life Science
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• v.7 no.2
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• pp.74-85
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• 2022

Organisms constituting a large proportion of marine ecosystems, ranging from bacteria to fish, exhibit fluorescence and bioluminescence. A variety of marine organisms utilize these biochemically generated light sources for feeding, reproduction, communication, and defense. Since the discovery of green fluorescent protein and the luciferin-luciferase system more than a century ago, numerous studies have been conducted to characterize their function and regulatory mechanism. The unique properties of fluorescent and bioluminescent proteins offer great potential for their use in a broad range of applications. This short review briefly describes the functions and characteristics of fluorescent and bioluminescent proteins, in addition to summarizing the recent status of their applications.

• Analytical Science and Technology
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• v.17 no.2
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• pp.163-172
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• 2004

The molecular size distribution and fluorescence properties of soil fulvic acids (FA) were characterized by using gel filtration chromatography (GFC) and luminescence spectroscopy. The objectives of this work were to fractionate the FA extracted from a forest soil into different nominal molecular size using GFC system and to characterize the fluorescence properties (excitation, emission and synchronous) of these fractions using luminescence spectrometer. The GFC column was calibrated with polyethylene glycols, acetone and dextrane Blue. The total permeation volume of the GFC system was 404 mL and the void volume 130 mL. The GFC molecular weight of the soil FA was in the range of 190~8,900 Dalton and the molecular weight at the peak on the chromatogram was 930 Dalton. The fluorescence intensity ratio ($I_{498nm}/I_{390nm}$) was found to be increased with an increasing molecular weight. This results may suggest that the fulvic acid fractions with high molecular weight have large amount of the condensed aromatic compound.

• Polymer(Korea)
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• v.32 no.4
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• pp.305-312
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• 2008

A novel TPC-PEG-TPC with active end-groups was obtained from the end-groups of polyethylene glycol (PEG) modified by terephthaloyl chloride (TPC). These active end-groups can link up with a rare earth ion, which is a luminescent center of a rare earth fluorescent complex. Complexes of Eu-PEG with novel ligands (TPC-PEG-PTC) were synthesized by the coordination of the active reactant (as the first ligand) and phenanthroline (as the second ligand) with $Eu^{3+}$.IR, $^1H$-NMR, element analysis, DSC, WAXD, fluorescent spectroscopy, TGA, and SEM were used to characterize the structure and properties of these complexes. The results showed that this type of complex is a heat storage material with the phase change character of polyethylene glycol (PEG) and the luminescent properties of europium. There was no thermal decomposition of the complex of Eu-PEG until $300^{\circ}C$. SEM showed that the complex of Eu-PEG can be dispersed in PE.

• Journal of the Mineralogical Society of Korea
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• v.17 no.2
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• pp.123-133
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• 2004

Carbonate minerals are examined by cathodoluminescence microscopy and chemical analysis to characterize the carbonate materials occurring in the Tertiary marine basin. The microscopic technique with cathodoluminescence gives new informations that are not obtainable by conventional microscopic techniques. The carbonate cements in sandstones appear to be uniform with transmitted light or with crossed prisms. but the inspection with cathololuminescence reveals foraminiferal tests and rhomb crystals in the carbonate cements. The chemical analysis indicates that the intense luminescence depends mainly on the presence of$ Mn^{ 2+}$ and $Fe^{2+}$ as activator ions, but the $Fe^{2+}$ also acts as an important quencher ion when Fe concentration in dolomite is over 10,000 ppm. The dolomites, which are rich in calcium, are formed at the early stage of diagenesis at a temperature of about 60 ～ $70^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.55 no.1
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• pp.55-60
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• 2018

In this study, quantum dots composed of $Mn^{2+}$ doped ZnS core and ZnS shell were synthesized using MPA precursor at room temperature. The ZnS: Mn/ZnS quantum dots were prepared by varying the content of MPA in the synthesis of ZnS shells. XRD, Photo-Luminescence (PL), XPS and TEM were used to characterize the properties of the ZnS: Mn/ZnS quantum dots. As a result of PL measurement using UV excitation light at 365 nm, the PL intensity was found to greatly increase when MPA was added at 15 ml, compared to the case with no MPA; the PL peaks shifted from 603 nm to 598 nm. A UV sensor was fabricated by using a sputtering process to form a Pt pattern and placing a QD on the Pt pattern. To verify the characteristics of the sensor, we measured the electrical properties via irradiation with UV, Red, Green, and Blue light. As a result, there were no reactions for the R, G, and B light, but an energy of 3.39 eV was produced with UV light irradiation. For the sensor using ZnS: Mn/ZnS quantum dots, the maximum current (A) value decreased from $4.00{\times}10^{-11}$ A to $2.62{\times}10^{-12}$ A with increasing of the MPA content. As the MPA content increases, the PL intensity improves but the electrical current value dropped because of the electron confinement effect of the core-shell.