• Applied Science and Convergence Technology
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• v.25 no.1
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• pp.19-24
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• 2016

In this study, we evaluated the change of electronic structure during redox process in cerium-doped $ZrO_2$ grown by sol gel method. By sol-gel method, we could obtain cerium-doped $ZrO_2$ in high oxygen partial pressure and low temperature. After post annealing process in nitrogen ambient, the film is deoxidized. We used spectroscopic and theoretical methods to analysis change of electronic structure. X-ray absorption spectroscopy (XAS) for O K1-edge and Density Functional Theory (DFT) calculation using VASP code were performed to verify the electronic structure of the film. Also, high resolution x-ray photoelectron spectroscopy (HRXPS) for Ce 3d was carried out to confirm chemical bond of cerium doped $ZrO_2$. Through the investigation of the electronic structure, we verified as followings. (1) During reduction process, binding energy of oxygen is increase. Simultaneously, oxidation state of cerium was change to 4+ to 3+. (2) Cerium 4+ and cerium 3+ states were generated at different energy level. (3) Absorption states in O K edge were mainly originated by Ce 4+ $f_0$ and Ce 3+, while occupied states in valance band were mainly originated from Ce 4+ $f_2$.

• Korean Journal of Optics and Photonics
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• v.2 no.4
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• pp.209-213
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• 1991

Recently, the developments in generating and amplifying ultrashort optical pulses $(ps=10^{-12}s or fs=10^{-15}s)$ have imposed on great advances in the time-resolved laser spectroscopy. Especially, the transient absorption spectroscopy has a wide application range and the main idea of this technique is pump & probe method. After the pump pulse makes the material an excited or a transient states, the probe pulse is sent through the material to measure the absorbance change due to the transient states. Here, if the absorbance change was measured by the time delay between pump & probe pulses, the dynamic information of the excited or the transient states (the transient abnsorption changes by time & wavelength) can be obtained. At our laboratory, the ultrashort optic1 pulse (

• Journal of Climate Change Research
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• v.7 no.3
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• pp.351-356
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• 2016

The carbon capture and storage (CCS), which collects and stores carbon dioxide in a geological site, is a promising option to mitigate climate change. However, there is the possibility of carbon dioxide leakage from the soil in the steps of collecting, transporting, and storing. To ensure the feasibility of this technology, it is important to monitor the leakage of carbon dioxide and to assess the potential impacts. As plants are sensitive to the changes in carbon dioxide in the soil environment, we can utilize plant parameter to detect the carbon dioxide leakage. Currently, chlorophyll a content is a conventional index indicating the changes in plants, however, this method is labor intensive and it only utilizes a small portion of leaves. To overcome its limitations, a simple spectroscopic parameter, DGCI (dark green color index), was suggested as an easy and quick indicator. In this study, we compared the values of chlorophyll a contents with DGCI from the experiment investigating the impacts of high underground $CO_2$ on grape plants. Results suggest that DGCI had high correlation with chlorophyll a contents and it has high potential to be utilized as an easy indicator to monitor plants' responses to $CO_2$ treatment.

• Journal of Magnetics
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• v.11 no.1
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• pp.12-15
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• 2006

Magnetic and electronic properties of reduced rutile titanium dioxide $(TiO_{2-\delta})$ thin films doped by Mn have been investigated. The present sol-gel-grown semiconducting $TiO_{2-\delta}:Mn$ films exhibit a ferromagnetic behavior at room temperature for a limited range of Mn content. The Mn-doped films have p-type electrical conductivity with the carrier concentration near $10^{19}\;cm^{-3}$. The observed room-temperature ferromagnetism is believed to be intrinsic but not related to free carriers such as holes. Oxygen vacancies are likely to contribute to the room-temperature ferromagnetism-trapped carriers in oxygen vacancies can mediate a ferromagnetic coupling between neighboring $Mn^{+3}$ ions. The energy band-gap change due to the Mn doping measured by spectroscopic ellipsometry exhibits a red-shift compared to that of the undoped sample at low Mn content. It is explainable in terms of strong spin-exchange interactions between Mn ion and the carrier.

• Journal of the Korean Chemical Society
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• v.42 no.2
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• pp.143-149
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• 1998

When anesthetics were added to a bacteriorhodopsin (bR) in the purple membranes, the 570 nm absorption band shifts to 480 nm. This anesthetic-induced spectroscopic change is reversible. The apparent pKa (6.3) of this equilibrium depends on the nature of the anesthetics in which bR is dispersed. The electric orientation measurements showed that the native bR is easily achieved by relatively small electric field which is oriented at $60^\circ$, while anesthetic-treated bR is not the case. These results demonstrate that the subtle changes in the chromophore and the protein structure surrounding the chromophore by anesthetics influence the spatial orientation of the charged residues in the protein matrix surrounding chromophore.

• Journal of the Korean institute of surface engineering
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• v.43 no.6
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• pp.289-296
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• 2010

The effect of organic additives, thiourea (TU), on the copper electroplated layer of large rectangular size was investigated through physical and various electrochemical techniques. It was found that TU had strong adsorption characteristics on the Ni substrate and affected the initial electroplating process by inducing surface reaction instead of mass transfer in the bulk solution. TU additives had its critical micelle concentration at 200 ppm in copper sulphate solution and showed abrupt change in morphological and electrochemical impedance spectroscopic results around this concentration, which could be related with the destruction of adsorption structure of TU-Cu(I) complex formed at the Ni substrate surface. By conducting a commercial electroplating simulation, when TU additives was included at cmc in the plating solution, it acted as a depolarizer for copper electrodeposition and was effective to reduce the unevenness of copper deposits between centre and edge region at high current densities of 10 ASD.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.320-321
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• 2006

In this work, impedance Spectroscopic analysis was applied to study the effect of plasma treatment on the surface of indium-tin oxide (ITO) anodes using $CF_4g$ as and to model the equivalent circuit for organic light emitting diodes (OLEDs) with the $CF_4$ plasma treatment of ITO surface at the anodes. This device with ITO/TPD/$Alq_3$/LiF/Al structure can be modeled as a simple combination of a resistor and a capacitor. The $CF_4$ plasma treatment on the surface of ITO shifts the vacuum level of the ITO as a result of which the barrier height for hole injection at the ITO/organic interface is reduced. The Impedance spectroscopy measurement of the devices with the $CF_4$ plasma treatment on the surface of ITO anodes shows change of values in parallel resistance ($R_p$) and parallel capacitance ($C_p$).

• Corrosion Science and Technology
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• v.8 no.3
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• pp.116-118
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• 2009

Korea Institute of Construction Materials founded Seosan Outdoor Exposure Test Site 2005 at Korea, which is a part of Worldwide Exposure Network (WEN). To evaluate the test site along with other exposure test sites, three different types of paints have been under real time weathering conditions at three major weathering test facilities around the world. Using these test specimens several spectroscopic experiments along with physical tests have been performed. Also acceleration tests have been performed using the same paints. The correlation of weathered paints among three different test facilities and accelerated test results has been compared. From the results the reliability of Seosan Weathering Test Facility and reasonable life time prediction tests are discussed.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.76.1-76.1
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• 2014

We present near-infrared spectroscopic and photometric observations of the nova V2468 Cyg taken from 2008 March 14 till 2008 November 11 following its outburst on 2008 March 7. The JHK spectra of the nova have been taken from the Mount Abu Infrared Observatory using the Near-Infrared Imager/Spectrometer. The early spectra are dominated by strong H I lines from the Brackett and Paschen series, Fe II, O I and C I lines, typical of Fe II type novae but after 46 days from outburst there is significant reduction in the strength of the C I lines and the spectra are dominated by He I lines. The FWHM of the Pa-beta and Br-gamma lines change from 2200-2300 km s-1 to 1700-1800 km s-1 after 12 days from outburst. Three additional small amplitude outbursts are seen near 110, 185 and 240 days in the V band light curve after the discovery. The upper limit for the ejecta mass for V2468 Cyg is estimated to be $5.2{\times}10-6Msun$.

• Journal of the Optical Society of Korea
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• v.18 no.4
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• pp.350-358
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• 2014

The collapse of Langmuir monolayers of arachidic acid (AA) on water at various rates of molecular area compression has been investigated in situ by imaging ellipsometry (IE). The thickness of the collapsed AA molecules, which are inherently inhomogeneous, was determined by IE with a spatial resolution of a few microns. For the analysis, we determined the dielectric function of AA monolayers from 380 to 1690 nm by conventional spectroscopic ellipsometry. Compression rates ranged from 0.23 to $0.94{\AA}^2/min$. A change of multilayer domains was observed in the in situ IE images. Lower compression rates resulted in more uniform collapsed films. Our experimental results correspond with previous theoretical simulations.