• Journal of Astronomy and Space Sciences
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• v.30 no.2
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• pp.87-90
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• 2013

We have investigated the X-ray emission from the shock-heated plasma of the Galactic supernova remnant Kesteven 69 with XMM-Newton. Assuming the plasma is at collisional ionization equilibrium, a plasma temperature and a column absorption are found to be kT ~ 0.62 keV and $N_H{\sim}2.85{\times}10^{22}\;cm^{-2}$ respectively by imaging spectroscopy. Together with the deduced emission measure, we place constraints on its Sedov parameters.

• Journal of the Korean Magnetics Society
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• v.20 no.5
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• pp.201-205
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• 2010

X-ray magnetic circular dichroism (XMCD) has been used as an important tool of magnetics due to its unique abilities to measure element-specific magnetic properties and to separate the orbital and the spin magnetic moments. These abilities allow researchers to access the microscopic origin of the magnetic properties of transition metal and rare earth compounds. In this report, I explain the principle of XMCD and the experimental set-up. Recent a few research examples using XMCD will be also introduced.

• Journal of Soil and Groundwater Environment
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• v.25 no.2
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• pp.9-15
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• 2020

This study was conducted to investigate the in situ formation of amorphous Fe oxides as a stabilization technology in As-contaminated soil. After addition of ferric nitrate and the neutralizing agent, most of extractable fractions of As in soil (i.e., SO₄^2- and PO₄^3--extractable As) was converted into As bound to amorphous Fe oxides. In addition, results of solubility bioavailability research consortium (SBRC) test indicated that a significant amount of As in untreated soil changed to a non-bioaccessible form after stabilization. The reason was attributed to the newly formed amorphous Fe oxides in the stabilized soil, which was confirmed by linear combination of fitting (LCF) using X-ray absorption spectroscopy (XAS) analysis. Interestingly, after five months of aging of the stabilized soil, ferrihydrite and schwertmannite newly formed in the soil were transformed to crystalline Fe oxides such as goethite, and further decrease in SBRC extractable fraction of As was observed. The results suggest that co-precipitated As with amorphous Fe oxides can be further immobilized with time, due to the crystallization of amorphous Fe oxides.

• Journal of the Korean Vacuum Society
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• v.20 no.4
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• pp.252-257
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• 2011

The ring formation and electronic properties of furan adsorbed on graphene layers grown on 6H-SiC (0001) has been investigated using atomic force microscopy (AFM), near edge X-ray absorption fine structure (NEXAFS) spectra for the C K-edge, and core level photoemission spectroscopy (CLPES). Moreover, we observed that furan molecules adsorbed on graphene could be used for chemical functionalization via the lone pair electrons of the oxygen group, allowing chemical doping. We also found that furan spontaneously form rings with one of three different bonding configurations and the electronic properties of the ring formed by furan on graphene can be described using by AFM, NEXAFS and CLPES, respectively.

• 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.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.164-164
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• 2000

Since Au-Pt alloys have various atomic structures depending upon composition and annealing temperature, it is very interesting to investigate the electronic structures of alloys. We studied the changes of the electronic structure I the Au-Pt alloys by x-ray absorption near edge spectroscopy (XANES). Two kinds of Au-Pt alloy samples were prepared by arc melting methods and ion-beam-mixing technique. The Pt L2, 3-edge and Au L2, 3-edge X-ray absorption spectra (XPS) were measured with the electron yield mode detector at the 3C1 beam line of the Pohang Light Source (PLS). It was found that there was a substantial decrease in the area of the Pt L2, 3 white lines compared with that of pure Pt. The observed decrease in white line area was attributed to an increase in the number of pure Pt. The observed decrease in white line area was attributed to an increase in the number of 5d-electrons at the Pt site upon alloy formation. However, the Au L2, 3 edge spectra for Au-Pt alloys are all similar to that of pure Au. This implies that the 5d hole count of Au is not changed by alloy formation with Pt.

• Journal of Pharmacopuncture
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• v.20 no.1
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• pp.36-44
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• 2017

Objectives: The goal of this study was to characterize Suvarna Bhasma Parada Marit by using the Ayurvedic test parameters, physico-chemical tests, and various instrumentation techniques. Methods: Suvarna Bhasma, an Ayurvedic formulation manufactured as per Bharat Bhaishajya Ratnakar 5/8357 (BBR), has been studied using various instrumentation techniques: X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), laser particle size distribution (PSD) analysis, fourier transform infrared spectroscopy (FT-IR), and atomic absorption spectroscopy (AAS), and physico-chemical parameters, such as the loss on drying (LOD), loss on ignition (LOI), and acid insoluble Ash (AIA) were determined. In addition, Ayurvedic tests, such as Rekhapurnatva (enterable in the furrows of the fingers), Varitaratwa (floatable over water), Nirdhoomta (smokeless), Dantagre Kach-Kach (gritty particle feeling between the teeth), were performed. Results: The XRD study showed Suvarna Bhasma to be crystalline in nature and to contain more than 98% gold. The mean size of the gold crystallites was less than 10 microns, and the morphology was globular and irregular. Suvarna Bhasma contains gold as its single and major element, with EDAX and FT-IR spectra showing that it is more than 98% pure gold. The moisture content (LOD) is less than 0.5%, the LOI is less than 2%, and the AIA is not less than 95%. The Ayurvedic tests, as specified above, helped to confirm the quality of Suvarna bhasma prepared as per the text reference (BBR). Conclusion: This chemical characterization of Suvarna Bhasma performed in this study by using modern instrumentation techniques will be helpful in understanding its pharmacological actions and will help in establishing quality protocols and specifications to substantiate the safety, efficacy & quality of Suvarna Bhasma.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.86-86
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• 2016

최근 포항가속기연구소 10A 빔라인에 Scanning Transmission X-ray Microscopy (STXM)가 완성되어 운영 중이다. Soft x-ray imaging 장치로서 기술적으로 Sample scanning 기법이 활용된다. 이는 Zone plate를 통해 집속된 빔이 샘플에 조사되고 검출되는 방식이다. 이러한 Scanning 기법을 활용하고 있는 10A STXM은 기본적으로 흡수분광기법 (x-ray absorption spectroscopy)을 이용하고 있다. 특히, 10A 빔라인 STXM은 최고 20 nm까지 공간분해능이 가능하다는 장점이 있다. 따라서 수십에서 수백 나노미터 크기의 시료들 또는 나노구조에 대한 물리화학적 상태 분석이 쉽게 이루어지고 있다. 주로 시료를 투과하면서 흡수되는 X-선 세기 대비를 맵핑하는 형식의 이미지 데이터와 더불어 X-선의 에너지를 조정함으로써 각 에너지에 해당하는 이미지스택을 결과로 얻게 된다. 이러한 이미지 결과로부터 시료의 나노크기에서 오는 물리화학적 상태를 분석하고 물리에서 바이오까지 다양한 분야의 실험 활용이 가능한 상태다.

• Applied Science and Convergence Technology
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• v.24 no.5
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• pp.151-155
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• 2015

The interfacial electronic structure between zinc phthalocyanine (ZnPc) and aluminumdoped zinc oxide (AZO) substrates has been evaluated by ultraviolet photoemission spectroscopy and angle-dependent x-ray absorption spectroscopy to understanding the molecular orientation of a ZnPc layer on the performance of small molecule organic photovoltaics (OPVs). We find that the ZnPc tilt angle improves the ${\pi}-{\pi}$ interaction on the AZO substrate, thus leading to an improved short-circuit current in OPVs based on phthalocyanine. Furthermore, the molecular orientation-dependent energy level alignment has been analyzed in detail using ultraviolet photoemission spectroscopy. We also obtained complete energy level diagrams of ZnPc/AZO and ZnPc/indium thin oxide.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.87-88
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• 2012

Metal oxide nanostructures have been applied to various fields such as energy, catalysts and electronics. We have freely designed one and two-dimensional (1 and 2-D) metal (transition metals and lanthanides) oxide nanostructures, characterized them using various techniques including scanning electron microscopy, transmission electron microscopy, X-ray diffraction crystallography, thermogravimetric analysis, FT-IR, UV-visible-NIR absorption, Raman, photoluminescence, X-ray photoelectron spectroscopy, and temperature-programmed thermal desorption (reaction) mass spectrometry. In addition, Ag- and Au-doped metal oxides will be discussed in this talk.