• Title/Summary/Keyword: IR difference spectra

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Starburst and AGN activity in local infrared luminous galaxies

  • Lee, Jong-Chul
    • The Bulletin of The Korean Astronomical Society
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    • v.36 no.2
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    • pp.55.1-55.1
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    • 2011
  • Luminous infrared galaxies (LIRGs; $L_{IR}$ > ${10^{11}}_{Lsun}$) are the most powerful objects in the local Universe. Previous work suggested that dust re-processing of starburst and/or active galactic nuclei (AGN) activity, triggered by galaxy interactions, is responsible for their enormous infrared emission. To understand the nature of LIRGs, it is essential to determine their spectral types. Optical spectral types of 115 ultraluminous infrared galaxies in the southern sky are presented using CTIO observations. The AGN fraction is on average 50% and increases with infrared luminosity. Near-infrared spectral types of 36 LIRGs are also presented based on AKARI observations. In the sample, 12 optically elusive buried AGNs are found. To investigate the evolutionary sequence of LIRGs, star formation histories of ~6000 LIRGs in the SDSS and IRAS/AKARI matched sample are derived by comparing observed optical spectra and stellar population models. AGN-dominated LIRGs are currently massive relative to starburst-dominated LIRGs, which originates from an enhancement of star formation at intermediate-ages. For ~1100 early-type LIRGs, optical and NIR fundamental planes (FPs) are constructed. The FP of LIRGs is significantly different from that of normal early-type galaxies, but the difference is minimized in low luminous and AGN-like LIRGs. These findings support that the importance of AGN is growing as infrared luminosity increases and that LIRGs follow at least in the high mass regime the standard evolutionary scenario: starburst LIRGs evolve into AGN LIRGs and finally into normal early-type galaxies.

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Investigation of Photoluminescence and Annealing Effect of PS Layers

  • Han, Chang-Suk;Park, Kyoung-Woo;Kim, Sang-Wook
    • Korean Journal of Materials Research
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    • v.28 no.2
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    • pp.124-128
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    • 2018
  • N-type porous silicon (PS) layers and thermally oxidized PS layers have been characterized by various measuring techniques such as photoluminescence (PL), Raman spectroscopy, IR, HRSEM and transmittance measurements. The top surface of PS layer shows a stronger photoluminescence peak than its bottom part, and this is ascribed to the difference in number of fine silicon particles of 2~3 nm in diameter. Observed characteristics of PL spectra are explained in terms of microstructures in the n-type PS layers. Common features for both p-type and n-type PS layers are as follows: the parts which can emit visible photoluminescence are not amorphous, but crystalline, and such parts are composed of nanocrystallites of several nm's whose orientations are slightly different from Si substrate, and such fine silicon particles absorb much hydrogen atoms near the surfaces. Light emission is strongly dependent on such fine silicon particles. Photoluminescence is due to charge carrier confinement in such three dimensional structure (sponge-like structure). Characteristics of visible light emission from n-type PS can be explained in terms of modification of band structure accompanied by bandgap widening and localized levels in bandstructure. It is also shown that hydrogen and oxygen atoms existing on residual silicon parts play an important role on emission stability.

Passive Remote Chemical Detection of SF6 Clouds in the Atmosphere by FTIR (수동형 FTIR 원격화학 탐지기를 이용한 SF6 오염운의 실시간 탐지)

  • Chong, Eugene;Park, Byeonghwang;Kim, Ju Hyun
    • Journal of the Korea Institute of Military Science and Technology
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    • v.17 no.1
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    • pp.8-14
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    • 2014
  • Brightness temperature spectra acquired from FTIR(Fourier Transform Infrared)-SCADS (Standoff Chemical Agent Detection System) could be available for detection and identification of the chemical agents and pollutants from different background. IR spectrum range of 770 to 1350 $cm^{-1}$ is corresponding to "atmospheric window". A 2-dimensional(2D) brightness temperature spectrum was drawn from combining each data point through automatic continuous scanning of FTIR along with altitude and azimuth. At higher altitude, temperature of background was decreased but scattering effect of atmospheric gases was increased. Increase in temperature difference between background and blackbody in SCADS at higher temperature causes to increases in peak intensity of $SF_6$. This approach shows us a possibility that 2D visual information is acquired from scanning data with a single FTIR-SCADS.

Repair of Plasma Damaged Low-k Film in Supercritical Carbon Dioxide (초임계이산화탄소를 이용한 플라즈마 손상된 다공성 저유전 막질의 복원)

  • Jung, Jae-Mok;Lim, Kwon-Taek
    • Clean Technology
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    • v.16 no.3
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    • pp.191-197
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    • 2010
  • Repair reaction of plasma damaged porous methyl doped SiOCH films was carried out with silylation agents dissolved in supercritical carbon dioxide ($scCO_2$) at various reaction time, pressure, and temperature. While a decrease in the characteristic bands at $3150{\sim}3560cm^{-1}$ was detectable, the difference of methyl peaks was not identified apparently in the FT-IR spectra. The surface hydrophobicity was rapidly recovered by the silylation. In order to induce effective repair in bulk phase, the wafer was heat treated before reaction under vacuum or ambient condition. The contact angle was slightly increased after the treatment and completely recovered after the subsequent silylation. Methyl groups were decreased after the plasma damage, but their recovery was not identified apparently from the FT-IR, spectroscopic ellipsometry, and secondary ion mass spectroscopy analyses. Furthermore, Ti evaporator was performed in a vacuum chamber to evaluate the pore sealing effect. The GDS analysis revealed that the open pores in the plasma damaged films were efficiently sealed with the silylation in $scCO_2$.

Physicochemical Characteristics of Silk Fibroin Degummed by Protease in Bacillus licheniformis II. Behavior in Aqueous Solution of Silk fibroin (Bacillus licheniformis 단백질 분해 효소에 의한 정련 견사의 특성 III. 견 피브로인 수용액의 거동)

  • 김영대;남중희
    • Journal of Sericultural and Entomological Science
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    • v.35 no.1
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    • pp.60-68
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    • 1993
  • It has been known that the silk degumming treated by hot alkali solution is easy to handle but is liable to yield poor-quality silk due to the degree of degumming loss, incomplete-degumming or over-degumming. Therefore, many studies have been carried out on the silk degumming by enzyme in order to improve the quality of silk. However, no attention has been paid to the physicochemical analysis of enzymatic degummed silk. In this paper, two different degumming methods, soap and enzymatic, are compared in aqueous solution state of silk fibroin. The results can be summarized as follows: There was no significant difference between two solutions on the bases of polarizing microscopy, TEM observation and SDS-PAGE. Spherulite of silk fibroin was not observed in polarizing microscopy, however the leaf-shape fibril structure was developed upon solidification. The size of spherulites of silk fibroin in TEM observation were 30~120nm with a wide range of size distribution. The intrinsic viscosity of enzymatic degummed fibroin solution was lower than that of soap degummed solution. This can be explained that the silk fibroin was more degraded by enzymatic degumming method compared with the soap degumming method. SDS-polyacrylamide gel electrophoresis showed that the fibroin molecule was composed of large component of molecule weight above 50 kd and small component of molecule weight about 20 kd. There was no difference in crystallinity between two degumming methods on the bases of results of DSC thermograms and IR spectra.

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Low-Temperature FTIR Spectroscopy of Bacteriorhodopsin and Phoborhodopsin

  • Kandori, Hideki;Furutani, Yuji;Shimono, Kazumi;Iwamoto, Masayuki;Sudo, Yuki;Shichida, Yoshinori;Kamo, Naoki
    • Journal of Photoscience
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    • v.9 no.2
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    • pp.106-109
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    • 2002
  • Archaeal rhodopsins possess retinal molecule as their chromophores, and their light-energy and light-signal conversions are triggered by all-trans to 13-cis isomerization of the retinal chromophore. Relaxation through structural changes of protein then leads to functional processes, proton pump in bacteriorhodopsin (bR) and transducer activation in phoborhodopsin (pR). It is known that sensory rhodopsins can pump protons in the absence of their transducers. Thus, there should be common and specific features in their protein structural changes for function. In this paper, our r ecent studies on pR from Natronobacterium pharaonis (ppR) by means of low-temperature Fourier-transform infrared (FTIR) spectroscopy are compared with those of bR. In particular, protein structural changes upon retinal photoisomerization are studied. Comparative investigation of ppR and bR revealed the similar structures of the polyene chain of the chromophore and water-containing hydrogen-bonding network, whereas the structural changes upon photoisomerization were more extended in ppR than in bR. Extended protein structural changes were clearly shown by the assignment of the C=O stretch of Asnl05. FTIR studies of a ppR mutant with the same retinal binding site as in bR revealed that the Schiff base region is important to determine their colors.

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Enhancement in the photocurrent of ZnO nanoparticles by thermal annealing

  • Byun, Kwang-Sub;Cho, Kyuong-Ah;Jun, Jin-Hyung;Seong, Ho-Jun;Kim, Sang-Sig
    • Journal of IKEEE
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    • v.13 no.1
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    • pp.57-64
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    • 2009
  • The optoelectrical characteristics of the ZnO nanoparticles (NPs) annealed in vacuum or oxygen condition from $200^{\circ}C$ to $600^{\circ}C$ were examined. Increased on-off ratio (or, the ratio of photocurrent to dark current) was observed when they were annealed at $300^{\circ}C$, $400^{\circ}C$ and $500^{\circ}C$ with the values enhanced about 4 orders compared to the as-prepared ZnO NPs in both annealing conditions, while the maximum efficiency was shown at the annealing temperature of $600^{\circ}C$ for the ZnO NPs annealed in vacuum with the value of 29.8 mA/W and at the temperature of $500^{\circ}C$ for those annealed in oxygen condition with the value of 40.3 mA/W. Photoresponse behavior of the ZnO NPs annealed in oxygen showed the sharp increase right after the ir exposure to the light followed by the slow decay and saturation during steady illumination, differing from the ZnO NPs annealed in vacuum which only exhibited the gradual increase. This difference occurred due to the curing effect of the oxygen vacancies. SEM images indicated no change in their morphologies with annealing, indicating the change in their internal structures by annealing, and most remarkably at $600^{\circ}C$. As for their photoluminescence(PL) spectra, the decrease of the deep-level(DL) emission was observed when they were annealed in oxygen at $400^{\circ}C$, and not at $200^{\circ}C$ and $600^{\circ}C$.

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An Ecochemical Study on Soil Sickness (인삼 연작 장해의 발생 원인 구명을 위한 생태화학적 연구)

  • 이춘영;임선욱
    • Journal of Ginseng Research
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    • v.1 no.1
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    • pp.51-58
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    • 1976
  • The phenomenon of sail sickness in the continuous cropping of ginseng is n serious problem for the cultivation practices and is an unelucidated subject scientifically. Present study is concerned mainly with ecochemical search on the cause of soil sickness in the continuous cropping of ginseng and the obtained results are summarized as follows: The humic substances isolated from both cultivated and uneulvidated soils with ginseng were compared with respect to its IR spectra but any difference which may be causative of sail sickness between them was not detected. In contrast, same saponin-like substances extracted from the ginseng cultivate soil in root tone were detected but not from the uncultivated soil. Presumably. the saponin like substances in the soils are originate) from the ginseng radices and are accumulaetd in root zone year by year, while the interrelation between the root exudate of ginseng and soil sickness is still obscure. According to a survey on the distributive Pattern of microflora in rhizosphere of ginseng radices the number of fungi is relatively diminished with the cul tivation years, while the number of actinomycetes is increased. It is supposed that the soil sickness in the continuous cropping of ginseng has any correlation between the activities of microflora in rhizosphere and the reef exudates.

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Color change of Zambian amethyst by heat treatment (잠비아산 천연 자수정의 열처리에 따른 색상변화)

  • Jun, Mi-Lee;Seo, Jin-Gyo;Kim, Young-Chool;Park, Jong-Wan
    • Journal of the Mineralogical Society of Korea
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    • v.22 no.2
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    • pp.97-106
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    • 2009
  • It is known that the natural amethyst is changed to citrine after heat treatment. However, when all amethyst samples from Zambia were heat-treated in the temperature range of $350{\sim}380^{\circ}C$ for 1 hour, the result was that five out of eight samples were changed to citrine and all the rest of samples became rock crystal quartz. These differences in the color appearance seem to be influenced by the original colors contained in the amethyst before the heat treatment. The amethyst containing yellow color changed to citrine and the amethyst without containing yellow color changed to rock crystal quartz after the heat treatment. The results compared after the instrumental analysis on the difference of color change, it showed the differences of peak intensity in 3,400 $cm^{-1}$ and the existence and non-existence of peak at the range of 5,200${\sim}$5,400 $cm^{-1}$ in FTIR. It revealed the difference in the quantity of Cr which is a trace element in the WD-XRF analysis. The identical result in the FTIR spectra before and after the heat treatment reveals that the heat treatment did not cause any change in the main composing elements or crystal structure.

Characterization of Sun Spangle Formation in the Transparent Baltic Amber by Heat Treatment (열처리를 통한 발틱 호박의 Sun spangle생성에 관한 연구)

  • Chung, Hyo-Jin;Seo, Jin-Gyo;Park, Jong-Wan
    • Journal of the Mineralogical Society of Korea
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    • v.22 no.4
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    • pp.395-405
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    • 2009
  • The maturity of amber matrix and inclusion was studied to explore the effect of heat treatment on the formation of the sun spangle in the transparent Baltic amber from Gdansk, Poland. Optical microscope revealed two types of inclusions in the original amber samples. The inclusions in the amber which had sun spangle were dramatically expanded by the heat treatment, comparing to those without sun spangle which contains fissure and shows different refractive index. The amber sample which didn't show sun spangle after the heat treatment showed a strong carbon related peak in TOF-SIMS spectra and weak oxygen related peak. it means that the maturity of this amber sample is comparatively higher than the one with spangle. The two amber samples show similar IR spectra before the heat treatment. However, the amber which had sun spangle exhibited an additional 1019 $cm^{-1}$ absorption peak and a more intense 887 $cm^{-1}$ peak. The different chemical compositions between the two types of amber is believed to be due to the different absorption spectra between 1000~600 $cm^{-1}$. According to the study of DSC analysis, the two samples show different DSC profiles. Although they have the same geological origin, their geological ages are different and have different chemical compositions. Thus, they exhibited different behavior after the heat treatment. The formation of sun spangle seemed to depend on the difference in the heat expansion rate of amber matrix with different maturity and chemical compositions.