• Bulletin of the Korean Chemical Society
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• v.13 no.6
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• pp.650-654
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• 1992

Absorption and fluorescence spectra are reported for four different 1 : 3 $Dy^{3+}$ : ligand systems in aqueous solution under mild alkaline pH conditions. The ligands included in this study are oxidiacetate, dipicolinate, iminodiacetate and methyliminodiacetate. The oscillator strengths for the 4f→4f multiplet-to-multiplet transitions are empirically determined from the absorption spectra and the intensity parameters ${\Omega}_{\lambda}$}(${\lambda}$ = 2, 4, 6) for the systems are also obtained by applying the Judd-Ofelt theorem to the observed oscillator strengths. The values of the intensity parameters for the systems are compared and discussed in terms of ligand structural properties to investigate how the intensity parameters can response to the minor changes in the ligand environment. In addition, the relative oscillator strengths for fluorescence are evaluated and compared to the results obtained from absorption spectra.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.105-106
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• 2013

Surface plasmon resonance (SPR) is classified into the propagating surface plasmon (PSP) excited on flat metal surfaces and the local surface plasmon (LSP) excited by metalnanoparticles. It is known that fluorescence signals are enhanced by these two SPR-fields.On the other hand, fluorescence is quenched by the energy transfer to metal (FRET). Bothphenomena are controlled by the distance between dyes and metals, and the degree offluorescence enhancement is determined by the correlation. In this study, we determined thecondition to achieve the maximum fluorescence enhancement by adjusting the distance of ametal nanoparticle 2D sheet and a quantum dots 2D sheet by the use of $SiO_2$ spacer layers. The 2D sheets consisting of myristate-capped Ag nanoparticles (AgMy nanosheets) wereprepared at the air-water interface and transferred onto hydrophobized gold thin films basedon the Langmuir-Schaefer (LS) method [1]. The $SiO_2$ sputtered films with different thickness (0~100 nm) were deposited on the AgMy nanosheet as an insulator. TOPO-cappedCdSe/CdZnS/ZnS quantum dots (QDs, ${\lambda}Ex=638nm$) [2] were also transferred onto the $SiO_2$ films by the LS method. The layered structure is schematically shown in Fig. 1. The result of fluorescence measurement is shown in Fig. 2. Without the $SiO_2$ layer, the fluorescence intensity of the layered QD film was lower than that of the original QDs layer, i.e., the quenching by FRET was predominant. When the $SiO_2$ thickness was increased, the fluorescence intensity of the layered QD film was higher than that of the original QDs layer, i.e., the SPR enhancement was predominant. The fluorescence intensity was maximal at the $SiO_2$ thickness of 20 nm, particularly when the LSPR absorption wavelength (${\lambda}=480nm$) was utilized for the excitation. This plasmonic nanosheet can be integrated intogreen or bio-devices as the creation point ofenhanced LSPR field.

• Archives of Pharmacal Research
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• v.4 no.2
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• pp.91-98
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• 1981

The substituent effects on the fluorescence of 2-(substituted anilino)benzoic acids and their aluminum chelate compounds were examined and satisfactory linear relationships between Hammett substitute constants, .sigma. and the lowest excited singlet energy levels were obtained. But fluorescence intensity only made a qualitative relationship with .sigma. values of substituent groups. Effects of solvents and metal ions on the native and metal chelate fluorescence of the above derivatives were also investigated.

• Bulletin of the Korean Chemical Society
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• v.23 no.7
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• pp.995-997
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• 2002

The synthesis and characterization of a nitrobenzene modified hexahomotrioxacalix[3]arene 1 are described.When calixarene 1 bound with ammonium ions carrying fluorescence group, the fluorescence of ammonium ions were effectively quenched and chang e of emission intensity provided the information of ammonium ion binding events to the calixarene 1.

• Journal of the Korean Applied Science and Technology
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• v.23 no.1
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• pp.70-76
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• 2006

The influence of fluorophor, scatterer, absorber in turbid materials by light scattering were interpreted for the scattered fluorescence intensity and wavelength, it is studied the molecular property by laser induced fluorescence spectroscopy. It can be found that the effects of optical property are penentrated in scattering media by the optical $parameters({\mu}s$, ${\mu}a$, ${\mu}t$, ${\gamma}$, ${\rho})$. The value of scattering coefficient ${\mu}s$ is large appeared by means of the increasing particles of scattering, it can be found that the slope appears exponentially as a function of distance from laser source to detector. It may also utilize in designing the best model for oil chemistry, laser medicine and application of medical engineering.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.5
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• pp.311-317
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• 2009

Due to extremely small device size and velocity scale, mixing in microchannel take place very slowly by way of molecular diffusion transport. Mixing enhancement becomes a central issue in microfluidics for biomedical and chemical applications. In this work, The optimization results and validation through experiment and fabrication. In this efficient micromixer design, it is essential to evaluate mixing efficiency with good precision. Mixing efficiency for Y-channel micromixer is measured by fluorescence intensity using LIF(Laser Induced Fluorescence) Confocal Microscope. The Y-channel micromixers are fabricated with polydimethylsiloxane(PDMS). Nile Blue A is injected into the micromixer as a fluorescence dye for measuring of fluorescence intensity by He/Ne laser. Throughout the experiments and computer simulation, accurate mixing efficiency evaluation process for a PDMS Y-channel micromixer is established.

• Journal of ILASS-Korea
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• v.4 no.4
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• pp.1-8
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• 1999

The concentration and spatial distribution of vapor phases in DI (Direct Injection) gasoline spray were measured quantitatively by exciplex fluorescence method. Fluorobenzene and DEMA (diethylmethylamine) in a solution of hexane were used as the exciplex-forming dopants. The fluorescence intensity of vapor phase were obtained by ICCD camera with the appropriate filter The relationship between fluorescence intensity and vapor concentration was induced fer the purpose of a quantitative analysis. The 2-D vapor/liquid images of fuel spray were captured under the evaporation condition, and the spatial distribution of vapor concentration was obtained. The spatial distribution of liquid phase had hollow-cone shape. And the vapor phase was widely distributed in the whole spray. The behavior of vapor phase was significantly affected by second flow such as entrainment, vortex, while that of liquid phase was scarcely affected.

• Journal of Environmental Science International
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• v.17 no.12
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• pp.1373-1380
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• 2008

Anthracene appended new host compounds have been synthesized by imine reaction. Fluorescent open chain host compounds Trisanthryl-tris(2-aminoethyl)imine 1 was synthesized from the reaction of tris(2-aminoethyl)amine and anthracene-9-carboxaldehyde in EtOH. Tris-10-chloroanthryl-tris(2-aminoethyl)imine 2 was synthesized from tris(2-aminoethyl)amine and 10-chloro-9-anthraldehyde in EtOH. The structures of all reaction product were identified by $^1H$ NMR, $^{13}C$ NMR, GC/MS, FAB Mass, IR spectrum and DSC. Cation complexation behavior was investigated by fluorescence spectroscopy measurements. The capability of transition metals cation recognition between fluorescent open chain host compound 1, 2 were investigated with $Co^{2+},\;Ni^{2+}\;and\;Cu^{2+}$. The fluorescence intensity was increased by host compounds corresponding guest cations. The relative order of fluorescence intensity changes were $Co^{2+}>Cu^{2+}>Ni^{2+}$. Compound 2 is very sensitive fluorescent sensor of $Co^{2+}$ ion.

• International Journal of Industrial Entomology and Biomaterials
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• v.48 no.1
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• pp.19-24
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• 2024

For over five millennia, humans have benefited from the valuable byproducts of Bombyx mori silkworms nourished on mulberry leaves and a multitude of potential applications remains available due to the diverse array of silkworm varieties. In this work, we discuss the utilization of Daehwangjam (DHJ), golden silk (GS), and Juhwangjam (JHJ), distinctive colored silks found in Korea, as chemosensors. These novel silks emit fluorescence under external stimuli and show a diminishing fluorescence intensity when exposed to HCl vapor. The considerable surface-to-volume ratio of these cocoons allows for the identification of 5 ppm, 300 ppm, and 3000 ppm HCl vapors through decreased fluorescence intensity. The results show the suitability of natural DHJ, GS, and JHJ for applications in biosensing applications.

• Journal of ILASS-Korea
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• v.8 no.4
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• pp.9-16
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• 2003

The Purpose of this study is to investigate the relationships between the local heat release rate and CH concentration have been investigated by numerical simulations of methane-air premixed flames. And simultaneous CH and OH PLIF(Planar Laser Induced Fluorescence) measurement has been also conducted for lean premixed flame as well as for laminar flames. Numerical simulations are conducted for laminar premixed flames and turbulent ones by using PREMIX in CHEMKIN and two dimensional DNS code with GRI mechanism version 2.11, respectively. In the case of laminar premixed flame, the distance between the peak of heat release rate and that of CH concentration is under $91{\mu}m$ for all equivalence ratio calculated in present work. Even for the premixed flame in high intensity turbulence, the distribution of the heat release rate coincides with that of CH mole fraction. For CH PLIF measurements in the laminar premixed flame burner, CH fluorescence intensity as a function of equivalence ratio shows a similar trend with CH mole fraction computed by GRI mechanism. Simultaneous CH and OH PLIF measurement gave us useful information of instantaneous reaction zone. In addition, CH fluorescence can be measured even for lean conditions where CH mole fraction significantly decreases compared with that of stoichiometric condition. It was found that CH PLIF measurements can be applicable to the estimation of the spatial fluctuations of heat release rate in the engine combustion.