• Journal of the Korean Chemical Society
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• v.47 no.5
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• pp.447-459
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• 2003

Generalized 2D correlation spectroscopy has been applied extensively to the analysis of spectral data sets obtained during the observation of a system under some external perturbation. It is used in various fields of spectroscopy including IR, Raman, UV, fluorescence, X-ray diffraction, and X-ray absorption spectroscopy (XAS) as well as chromatography. 2D hetero-spectral correlation analysis compares two completely different types of spectra obtained for a system under the same perturbation. Because of the wide range of applications of this technique, it has become one of the standard analytical techniques for the analytical chemistry, physical chemistry, biochemistry, and so on, and for studies of polymers, biomolecules, nanomaterials, etc. In this paper, we will introduce the principle of generalized 2D correlation spectroscopy and its applications that we have studied.

• Journal of the Korean Ceramic Society
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• v.41 no.6
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• pp.476-480
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• 2004

AZO (Al-doped ZnO) thin films were deposited on glass by pulsed magnetron sputtering method, and their structural, electrical and optical properties were investigated. XRD patterns showed that a highly c-axis preferred AZO film was grown in perpendicular to the substrate when pulse frequency of 30 ㎑ was applied to the target. Microstructure of thin films showed that the fibrous grain of tight dome shape was grown. The deposition rate decreased linearly with increase of pulse frequency, and the lowest resistivity was 8.67${\times}$10$\^$-4/ $\Omega$-cm for the film prepared at pulse frequency of 30 ㎑. The optical transmittance spectra of the films showed a very high transmittance of 85∼90%, within visible wavelength region and exhibited the absorption edge of about 350 nm. The characteristics of the low electrical resistivity and high optical transmittance of AXO films suggested a possibility for the application to transparent conducting oxides.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.669-669
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• 2013

Hierarchical N doped TiO2 nanostructured catalyst with micro, meso and macro porosity have been synthesized by a facile self-formation route using ammonia and titanium isopropoxide precursor. The samples were calcined in different calcination temperature ranging from $300^{\circ}C$ to $800^{\circ}C$ at slow heating rate ($5^{\circ}C$/min) and designated as NHPT-300 to NHPT-800. $TiO_2$ nanostructured catalyst have been characterized by physico-chemical and spectroscopy methods to explore the structural, electronic and optical properties. UV-Vis diffuse reflectance spectra confirmed the red shift and band gap narrowing due to the doping of N species in TiO2 nanoporous catalyst. Hierarchical macro porosity with fibrous channel patterning was observed (confirmed from FESEM) and well preserved even after calcination at $800^{\circ}C$, indicating the thermal stability. BET results showed that micro and mesoporosity was lost after $500^{\circ}C$ calcination. The photocatalytic activity has been evaluated for methanol oxidation to formaldehyde in visible light. The enhanced photocatalytic activity is attributed to combined synergetic effect of N doping for visible light absorption, micro and mesoporosity for increase of effective surface area and light harvestation, and hierarchical macroporous fibrous structure for multiple reflection and effective charge transfer.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.11
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• pp.1019-1024
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• 2009

Visible-light-active $TiO_2-_xN_x$ nanoparticles with a homogeneous anatase crystalline structure were successfully prepared through a hydrolysis of $TiCl_4$ with ammonia solution. The samples were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), $N_2$-sorption, and UV-vis diffuse reflectance spectra (DRS) techniques. The light absorption onset shifted from 390 nm on pure $TiO_2$ to the visible region at 530 nm on nitrogen-doped $TiO_2$. A clear decrease in the band gap was deduced from the DRS results. The photocatalytic activity was evaluated from the photodegradation of congo red solution under visible light irradiation. The photocatalyst showed the highest photocatalytic activity at an optimal value of nitrogen doping concentration. This was suggested that the nitrogen doping should have an important effects on the improvement of photocatalytic activity.

• Macromolecular Research
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• v.14 no.2
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• pp.173-178
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• 2006

Poly(3-(2-hydroxyethyl)thiophene) (P3HET) was synthesized using oxidative coupling polymerization that involved the protecting and deprotecting of hydroxyl groups but not the chlorine substitution or oxidative decomposition of the hydroxyl groups. The resulting P3HET exhibited good solubility in aprotic solvents, in contrast to the insoluble polymer product synthesized directly from the monomer, 3-(2-hydroxyethyl)thiophene (3HET). P3HET had low conductivity due to the strong hydrogen bonding of its hydroxyl groups. The ester-functionalized poly(3-(2-acetoxyethyl)thiophene) and poly(3-(4-pentylbenzoateethyl)thiophene) were also prepared with reasonably high molecular weights in order to examine how this functionalization modified the physical and chemical properties of P3HET. These polymers exhibited better solubility in common solvents and higher conductivity than P3HET. All these polymers exhibited bathochromic shifts of their film state absorption maxima with respect to those found in the UV-visible spectra of their solution phases. The extent of the bathochromic shift was found to vary with the lengths of the side chains of the ester-functionalized polymers.

• Applied Biological Chemistry
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• v.25 no.4
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• pp.224-231
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• 1982

${\alpha}-Tocopherol$ was found to be a fluorescent probe in determination of the phasetransition temperature of liposome. Since this was a discovery of a new aspect of ${\alpha}-tocopherol$ as an important biochemical molecule, its molecular spectroscopic characterization was carried out in order to obtain some informations on its spectral and, structural properties in various media, anticipating that the compound may entertain a wide applications in biochemical systems as a spectroscopic probe. Two species of α${\alpha}-tocopherol$, monomer and dimer, were found to exist in organic media, especially in solvents of nonhydrogen bonding ability. Monomer with maximum UV-absorption around $(291{\sim}294nm)$ is highly fluorescent, while dimer which is formed by intermolecular hydrogen bonds and absorbes with spectral peak at 298nm is nonfluorescent. ${\alpha}-tocopherol$ incorporated to liposome exhibits emission property quite different from that in various organic media showing broad and red-shifted fluorescence excitation and emission spectra. This spectral abnormality is to be interpreted to arise from chromanolate-type ion, H-dissociated ${\alpha}-tocopherol$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.316-319
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• 2000

In the case of immobilizing of glucose oxidase into polypyrrole (PPy) using electrosynthesis, the glucose oxidase (GOx) forms a coordinate bond with the polymer's backbone. However, because of intrinsic insulation and net-chain of the enzyme, the charge transfer and mass transport are obstructed during the film growth. Therefore, the film growth is dull. We synthesized the enzyme electrode by electropolymerization added some organic solvent, A formative seeds of film growth is delayed by adding the solvent. The delay is induced by radical transfer between the solvent and pyrrole monomer. In the case of adding ethanol, the radical transfer shares the contribution of dopant between electrolyte anion and GOx polyanion. This may lead to increase amount of immobilized the enzyme in ppy. However, adding tetrahydrofuran (THF), the radical transfer is more brisk, resulting in short chained polymer. Therefore, the doping level is lowered and then amount of immobilized of enzyme is decreased. For the UV absorption spectra of synthetic solution before synthesis and after, in the case of ethanol added, the optical density was slightly decreased for the GOx peaks. It suggests amount of GOx in the solution was decreased and amount of GOx in the film was increased. We established qualitatively that amount of immobilization can be improved by adding a little ethanol in the synthetic solution. It is due to radical transfer reaction. The radical transfer shares the contribution of dopant between small and fast electrolyte anion and big and slow GOx polyanion.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.317-318
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• 2008

Cu-Pc유기물 반도체를 얼 진공증착기술로 유리기판위에 40 nm 두께로 적층하였다. 상온에서 적층한 박막과 상온에서 적층한 후 $250^{\circ}C$ 이상의 온도로 후열 처리한 박막과 박막 적층 시 기판의 온도를 $250^{\circ}C$로 고정하여 적층한 박막들을 상호 비교 분석하였다. 적층된 Cu-Pc의 박막의 온도조건에 따라 X-ray diffraction(XRD)의 결정 특성이 $\alpha$-phase와 $\beta$-phase로 뚜렷이 구분되었으며， 자외선-가시광선 영역의 광 흡수도(UV-visible absorption spectra)와 field emission scanning electron microscopy(FE SEM)를 이용하여 결정성장 방향 및 표면 특성 변화를 비교조사하였다.

• Journal of the Korean Ceramic Society
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• v.49 no.2
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• pp.135-141
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• 2012

To improve the visible-light induced photocatalytic application performances of $TiO_2$, in this study, the $NiS_2$ modied $TiO_2$ composites were prepared by two methods: hydrothermal method and sol-gel method. The composites were denoted as hs-$NiS_2$/$TiO_2$, and sg-$NiS_2$/$TiO_2$ and characterized by XRD, UV-vis absorbance spectra, SEM, TEM, EDX, and BET analysis. The photocatalytic activities under visible light were investigated by the degradation of methyl orange (MO). The photodegradation rate of methyl orange under visible light with $NiS_2$/$TiO_2$ composites was markedly higher than that of pure $TiO_2$, and the effect of hs-$NiS_2$/$TiO_2$ composites was better than that of sg-$NiS_2$/$TiO_2$. The results indicate that the hydrothermal process could partly inhibit the agglomeration of $NiS_2$/$TiO_2$. Thus, the dispersion of nanoparticles was improved, and that the promoting effect of $NiS_2$ could extend the light absorption spectrum toward the visible region.

• Journal of the Korean Ceramic Society
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• v.51 no.3
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• pp.162-169
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• 2014

This paper introduces a microwave-assisted synthesis method to prepare hybrid $Bi_2Se_3-GR/TiO_2$ nanocomposites, which exhibit superior properties over single component materials. The as-prepared composites were characterized by XRD, UV-vis absorbance spectra, SEM,TEM, EDX, and BET analyses, revealing uniform covering of the graphene nanosheet with $Bi_2Se_3$ and $TiO_2$ nanocrystals. For visible light photocatalysis of Rh.B, a significant enhancement in the reaction rate was consequently observed with $Bi_2Se_3-GR/TiO_2$ composites. The degradation rate($k_{app}$) obtained for sonophotocatalysis was $6.8{\times}10^{-3}min^{-1}$, roughly 2.2 times better than that of VL photocatalysis under higher concentrations of Rh.B. The sonophotocatalysis was faster due to greater formation of reactive radicals as well as an increase of the active surface area of the $Bi_2Se_3-GR/TiO_2$ composites. The high activity is attributed to the synergetic effects of high charge mobility and red shift of the absorption edge of $Bi_2Se_3-GR/TiO_2$.