• Journal of the Optical Society of Korea
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• v.14 no.4
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• pp.298-304
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• 2010

The pair-induced quenching (PIQ) effect in a highly doped bismuth oxide-based erbium-doped fiber amplifier (EDFA) was theoretically and experimentally investigated. In the theoretical investigation, the bismuth oxide-based EDFA was modeled as a 6-level amplifier system that incorporated clustering-induced concentration quenching, cooperative up-conversion, pump excited state absorption (ESA), and signal ESA. The relative number of paired ions in a highly doped bismuth oxide EDF was estimated to be ~6.02%, determined by a comparison between the theoretical and the experimentally measured gain values. The impacts of the PIQ on the gain and the noise figure were also investigated.

• Rapid Communication in Photoscience
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• v.2 no.1
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• pp.34-37
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• 2013

Two novel antenna complexes of $Eu^{III}$ with 1-naphthoic acid (NA) as primary ligand and two aromatic N-donor ligands namely N-hexyl-N-(pyridin-2-yl) pyridin-2-amine (1) and 4-((dipyridin-2-ylamino)methyl)benzoic acid (2) have been synthesized and characterized by various spectroscopic techniques. The room-temperature (298 K) photoluminescence spectrum of $Eu^{III}$ complexes composed of typical line like emissions, assigned to transitions between the first excited state $^5D_0$ to the $^7F_J$ (J = 0-4), resulting in red emission along with the residual emission from the 1-naphthoic acid moiety in the blue region. The determined CIE color coordinate value for the complex 2 is (x = 0.36, y = 0.34), which is in white region.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.67.1-67.1
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• 2018

We present high-resolution near infrared (IR) spectra of two candidate planetary nebulae (PNe) that were serendipitously found toward the Galactic center (GC). Our spectra obtained using GNIRS on Gemini North reveal strong Br ♑ and He I recombination lines. In one of the targets, we confidently detect Pa ♌ emission. Based on Br ♑ and Pa ♌ lines, we estimate a foreground reddening to be Av=27 mag, which confidently puts this object at the GC distance. Along with the presence of highly excited emission lines such as [S IV], [Ne III], [Ne V], and [O IV] detected in the mid-IR spectra from the Spitzer Space Telescope, and the extended emission in the Pa ♋ narrow-band image from the Hubble Space Telescope, this makes it the first spectroscopically confirmed PN in the GC.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1999.11a
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• pp.95-98
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• 1999

This paper describes preliminary discussions on spatial distribution of NO density, which is mostly contained in simulated NOX exhaust, between a wire-cylinder geometry discharge gaps by using Laser Induced Fluorescence(LIF) Spectroscopy. Spatial distribution of NO density will be measured with varying NO concentrations from 166 to 644[ppm] and diameters of central electrode from 6 to 10mm. Pulsed Nd:YAG laser, Optical Parametric Oscillator(OPO), and Frequency Doubler are used to excite NO molecules to their excited state.

• Rapid Communication in Photoscience
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• v.3 no.1
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• pp.1-15
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• 2014

We summarize recent studies on photoinduced electron- and energy-transfer processes of various supramolecules including imide group(s) as a component. Recently, imides have been employed in various functional molecular systems, because of their excellent photophysical and electron accepting properties. Our research group also employed imides in various supramolecular systems such as donor-acceptor dyads, quantum dots, DNA, and so on. First, we summarize fundamental properties of imides such as photophysical and electrochemical properties. Then, photoinduced processes of imides in the supramolecular systems are described to show their applicability in the various fields.

• Rapid Communication in Photoscience
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• v.2 no.3
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• pp.76-78
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• 2013

Photoaddition reactions of aromatic carbonyl compounds with silyl thioketene acetals have been explored. The results of this study show that the acetonphenone react with dimethyl substituted silyl thioketene acetal competitively via either single electron transfer (SET)-desilylation or [2+2]-cycloaddition pathways to produce b-hydroxyester and oxetanes. In contrast, photochemical reactions of the benzaldehyde with dimethyl substituted silyl thioketene acetal mainly lead to the formation of oxetanes arising by [2+2] cycloaddition. A comparison of the results with those of silyl ketene acetal revealed that replacement of sulfur atom in ${\alpha}$-silyl donor substrate bring about dramatic changes in chemoselectivities as well as excited state reaction mechanism.

• Journal of Photoscience
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• v.4 no.1
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• pp.1-5
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• 1997

A hitherto unknown diphenylbutadiene analog viz. 1-(p-N,N-dimethylaminophenyl)-4-phenyl-2-methyl-1E,3E-butadiene (10) has been prepared and its absorption, excitation, and fluorescent emission properties in different media including various organic solvents and aqueous bovine serum albumin (BSA) have been studied. For comparision, these properties have also been investigated for the parent diphenylbutadiene (2). Diene 10 exhibits solvent polarity/polarizability-sensitive fluorescence properties ($\lambda$$_{max}$, $\Phi$$_f$, $\tau$$_f$, K$_f$, f). It also binds to the hydrophobic domains of aqueous bovine serum albumin (BSA) with a binding constant of 3.89 x 10$^4$ M$^{-1}$. The relative fluorescence quantum yield of 10 increases, while, the fluorescence lifetime decreases with increasing concentration of-BSA. The results highlight the polar character of the singlet excited state of diphenylpolyenes and the utility of 10 as fluorescence probe for studying microenvironments of organized assemblies and biological supramolecular structures.

• Journal of Photoscience
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• v.1 no.2
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• pp.119-122
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• 1994

$PdCI_2(PPh_3)_2$-catalyzed photolysis of 1-phenyl-4-(pentamethyldisilanyl)buta-1,3-diyne (1) in dry benzene gives 1,4-disilacyclohexa-2,5-diene type dimerization products(3-6) via silacyclopropene. The silacyclopropene is formed from the singlet excited state of 1 and this silacyclopropene reacts with $(PPh_3)_2Pd^0$to form palladasilacyclobutene. In this reaction, the silylene-palladium complex is generated and reacts with 1 to give another silacyclopropene. $PdCI_2(PPh_3)_2$catalyzed photolysis of 1 with other alkynes supports the involvement of this silylene complex.

• Textile Coloration and Finishing
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• v.19 no.2
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• pp.1-6
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• 2007

In order to improve the light fastness of a natural colorant berberine, several natural antioxidants such as gallic acid, L-ascorbic acid, and ${\alpha}-tocopherol$ were applied by aftertreatment method. Even though the increase in light fastness of berberine colorant was not substantial, L-ascorbic acid was the most effective. It was considered that this improvement of the light fastness was due to high antioxidation action of L-ascorbic acid to colorant, which led very highly excited species of the colorant formed by photo-energy to return to the original stable state without being decomposed.

• Fibers and Polymers
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• v.6 no.2
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• pp.127-130
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• 2005

Intrinsic UV reflection and fluorescence behaviors of polycarbonate, polyurethane and poly(ethylene terephthalate) films were investigated in order to characterize the interaction of water in these films. During water sorption process, UV reflection spectra of polycarbonate and polyurethane films showed little peak position changes. Fluorescence emission spectra of polycarbonate films showed red spectral shifts from 332 nm with water immersion time. This red-shifted peak could be due to phenyl-2-phenoxybenzoate, which is one of the major thermal degradation products in polycarbonate. Fluorescence peaks of polyurethane films appeared at two different positions and the ratio of these peak intensities increased with increasing immersion time. In the case of PET films, the UV reflection spectrum showed the peak intensity around 340 nm to change in response to water sorption. The fluorescence near 388 nm probably due to ground state dimer exhibited sensitivity with water sorption, when excited at 340 nm.