• Title/Summary/Keyword: UV-Vis absorption

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Loading Effect of Ag Nanoparticles on Photocatalytic Activity of TiO2 Nanorod Arrays Prepared by Hydrothermal Method

  • Kwangmin Lee;Daeheung Yoo;Ahmad Zakiyuddin
    • Archives of Metallurgy and Materials
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    • v.66 no.3
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    • pp.751-754
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    • 2021
  • Rutile-TiO2 nanorod thin films were formed on Ti disks via alkali treatment in NaOH solutions followed by heat treatment at 700℃. Ag nanoparticles were loaded on nanorods using a photo-reduction method to improve the photocatalytic properties of the prepared specimen. The surface characterization and the photo-electrochemical properties of the Ag-loaded TiO2 nanorods were investigated using a field-emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS), UV-Vis spectroscopy and electrochemical impedance spectroscopy (EIS). The TiO2 nanorods obtained after the heat treatment were 80 to 180 nm thick and 1 ㎛ long. The thickness of the nanorods increased with the NaOH concentration. The UV-Vis spectra exhibit a shift in the absorption edge of the Ag-loaded TiO2 to the visible light range and further narrowing of the bandgap. The decrease in the size of the capacitive loops in the EIS spectra showed that the Ag loading effectively improved the photocatalytic activity of the TiO2 nanorods.

Investigation of Oxidation Methods of Organic Radical Polymer for Cathode Material in Lithium Ion Batteries (리튬이차전지 양극재인 유기라디칼 고분자의 산화법에 대한 연구)

  • Lee, Ilbok;Kim, Younghoon;Moon, Ji-Yeon;Lee, Chul Wee;Kim, Daeun;Ha, Kyoung-Su;Lee, Dong Hyun;Son, Hyungbin;Yoon, Songhun
    • Polymer(Korea)
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    • v.38 no.6
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    • pp.827-831
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    • 2014
  • An organic radical polymer (ORP) was prepared by radical polymerization and following oxidation into nitroxyl radical. Two different oxidation methods were employed and their radical concentrations were measured using electroparamagnetic resonance spectroscopy (EPR) and UV-visible absorption (UV-vis) spectroscopy. From these measurements, $H_2O_2-Na_2WO_4$ oxidation method exhibited a complete oxidation, which resulted in 97.6% spin concentration. Also, it was revealed that convenient and cheap UV-vis measurement was useful for preliminary radical concentration comparison. After applied as a cathode material in lithium ion batteries, ORP electrode showed a high initial capacity ($110mAh\;g^{-1}$), a good initial efficiency (96%), a very high rate performance (70% charging during 1.2 min) and stable cycle performance.

Preparation and photocatalytic degradation of CNT/TiO2 composites using MWCNT and various titanium alkoxide precursors (MWCNT와 여러가지 티탄알콕사이드 전구체를 사용하여 CNT/TiO2 복합체의 제조와 광촉매분해)

  • Chen, Ming-Liang;Zhang, Feng-Jun;Oh, Won-Chun
    • Analytical Science and Technology
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    • v.21 no.6
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    • pp.553-561
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    • 2008
  • $CNT/TiO_2$ composites were prepared by using multiwall carbon nanotubes (MWCNT) and various titanium alkoxide precursors. The composites were comprehensively characterized by scanning electron microscopy (SEM), field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX) and UV-vis absorption spectroscopy. The photoactivity of the prepared materials under UV irradiation, was tested using the conversion of MB from model aqueous solution. Finally, according to the results of methylene blue (MB) removal experiment, we could see that sample CTOS have better MB removal effect than samples CTIP and CTPP.

UV Absorption of Nano-thick $TiO_2$ Prepared Using an ALD (ALD 방법으로 제조된 나노급 $TiO_2$에 의한 자외선 차단효과 연구)

  • Han, Jeung-Jo;Song, Oh-Sung;Ryu, Ji-Ho;Yoon, Ki-Jeong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.8 no.4
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    • pp.726-732
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    • 2007
  • We fabricated UV absorption functional $10{\sim}50nm-TiO_{2-x}/quartz$ structures layer using ALD (atomic layer deposition) method. We deposited $10nm-TiO_{2-x}$ layer on quartz substrate using ALD, and film thickness was determined by an ellipsometer. The others specimen thickness was controlled by ALD time lineally. We characterized controlling phase UV and visible optical property using an X-ray difractometer, a UV-VIS-IR spectrometer and a digital camera. $ALD-TiO_{2-x}$ layers were non-stoichiometric $TiO_{2-x}$ form and amorphous phases comparing with bulk $TiO_2$. While the conventional bulk $TiO_2$ had band gap of $3.0{\sim}3.2eV$ resulting in absorption edges at 380 nm and 415 nm, $ALD-TiO_{2-x}$ layers showed absorption edges at 197 nm and 250 nm. Therefore, our nano-thick $ALD-TiO_{2-x}$ was able to absorb shorter UV region and showed excellent transmittance in visible region. Our result implies that our newly proposed nano-thick $TiO_{2-x}$ using ALD process may improve transmittance in visible rays and be able to absorb shorter UV light effectively.

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The study on the spectroscopic and electrical properties of Azomethine compounds (Azomethine계 화합물의 분광학적 특성과 전기적 특성에 관한 연구)

  • Baek, Dae-Jin;Oh, Won-Chun;Ko, Young-Shin
    • Analytical Science and Technology
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    • v.8 no.3
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    • pp.249-258
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    • 1995
  • The polymers, polyazine, polyazomethine ( I ) and polyazomethine ( II ) were prepared by the condensation of p-benzoquinone with hydrazine hydrate, p-phenylenediamine and diaminomaleonitrile in DMSO, respectively. The IR spectra of these polymers showed a characteristic peak of schiff base (-C=N-) at about $1600cm^{-1}$. These polymers dissolved in concentrated sulfuric acid showed UV/VIS absorption near 300nm indicatiog the presence of iminium ion(>$C\limits^{\small\oplus}=NH-$). Another UV/VIS absorption band in the region of 350~415nm was shown presumably due to the charge transfer transition in the molecule. The electrical conductivities of polyazine, polyazomethine ( I ) and ( II ) were measured. The self-electrical conductivity of these was found to be about $10^{-14}{\sim}10^{-11}{\Omega}^{-1}cm^{-1}$ and these polymers doped with $I_2$ showed the maximum conductivity of about $10^{-2}{\Omega}^{-1}cm^{-1}$.

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A Study on the Properties of Langmuir-Blodgett Films of Polyamic Acid containing p-Methoxyazobenzene (p-Methoxyazobenzene을 함유한 Polyamic acid의 Langmuir-Blodgett막 물성에 관한 연구)

  • Park, Keun-Ho;Lee, Seong-Rak
    • Journal of the Korean Applied Science and Technology
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    • v.15 no.1
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    • pp.55-62
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    • 1998
  • The absorption spectra of polyamic acid containing p-methoxyazobenzene in a mixture of N, N-dimethylacetamide(DMAC) and benzene(1:1 by volume) solution was induced photoisomerization by UV and visible light irradiation. This solution is influenced on temperature according to measure by UV-Vis Spectrophotometer. Ultra thin film of polyamic acid containing p-methoxyazobenzene was prepared on the hydrophilic quartz plate by Langmuir-Blodgett(LB) method. The precursor LB film was heated in a vacuum dry oven at $120^{\circ}C$ in order to convert it into the LB film of polyimide. The absorption spectra of LB films were also induced photoisomerization by UV and visible light irradiation.

A study on the identification of ruby and garnet by optical method (광학적 방법에 의한 루비와 가넷의 감별법에 관한 연구)

  • Hwang Ji-Ho;Choi Jong-Koen
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.15 no.5
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    • pp.182-187
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    • 2005
  • The FT-IR absorption spectrum by the lattice vibrations of ruby and garnet obtained from FT-IR shows quite different characteristics. By the UV-VIS spectroscopy it was found that the ruby has two transmission bands in red and blue region, while garnet has only one transmission band in red region. The color filter to distinguish ruby from garnet was developed and named HWANG JI HO filter. Through the HWANG JI HO filter, ruby was shown in blue color and garnet was shown in dark red color because of the only the blue region transmittance of the filter. Other red stones, such as spinel, tourmaline were shown in dark red color like as garnet. The ruby could be recognized easily from the red stone.

Preparation and Characterization of Cy3 Dye with Various Counter Cations (다양한 상대 양이온을 갖는 Cy3 염료의 제조 및 특성 연구)

  • Lee, Sang Dong;Hyun, Dong Kyoun;Jeong, Yeon Tae
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.28 no.5
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    • pp.314-319
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    • 2015
  • In this research, we focused on the development of cy3 dye with high thermal stability and good solubility for LCD color filter. Cy3 dyes were prepared through the synthetic procedure of two steps. The synthesized cy3 dyes were characterized by using NMR, FT-IR, UV/Vis spectroscopy, and TGA. These cy3 dyes showed maximum absorption wave length (${\lambda}_{max}$) in the range of 549~555 nm in UV/Vis spectrum. And we confirmed that solubility characteristics and thermal stability of cy3 dyes were dependent on the structure of counter cation. Cy3 dyes with methyl counter cation and ethyl counter cation have good solubility in organic solvents such as chloroform, ethanol, and PGME. Moreover, Cy3 dye with ethyl counter cation gave excellent thermal stability in TGA thermograms. And Cy3 dye with ethyl counter cation showed good result in photoresist film test.

A SPECTROSCOPIC STUDY OF THE OPTICAL PROPERTIES OF VARIOUS PAPERS MADE FROM RECLAIMED FIBRES

  • Ingegerd Forsskahl;Carola Olkkonen;Henrik Tylli
    • Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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    • 1999.04b
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    • pp.296-301
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    • 1999
  • Different papers such as toilet and towel tissue, newsprint and copy paper made from reclaimed fibres were characterized using UV-VIS reflectance and fluorescence spectroscopy. The emission properties of the extracts of the papers were also evaluated. Photochemical irradiation at ambient temperatures, and thermal aging of the copy papers at 105$^{\circ}C$ and 150$^{\circ}C$ were performed. Post-colour numbers (PC) were calculated from the reflectance values measured from the corresponding UV-VIS reflectance spectra. Light absorption coefficient spectra were calculated before and after irradiation, and the changes in absorption coefficient were related to the content of chromophores in the papers. Photochemical and thermal discolouration of the copy papers, similar to that of virgin fibres, was readily observed. The influence of changes in the concentrations of fluorescent brightening agents and dyes on the spectral properties was also assessed. Photostabilization studies of the copy papers were performed with the use of polymer additives polyethylene glycol (PEG) and polytetrahydrofuran (PTHF).