• Title, Summary, Keyword: Mid infrared spectroscopy

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A Gemini/GMOS-IFU Spectroscopy of E+A Galaxies in the Mid-infrared Green Valley: On the Spatial Distribution of Young Stellar Population

  • Lee, Gwang-Ho;Lee, Myung Gyoon;Bae, Hyunjin;Sohn, Jubee;Ko, Youkyung;Lee, Jaehyung;Kim, Eunchong;Cho, Brian S.
    • The Bulletin of The Korean Astronomical Society
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    • v.41 no.2
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    • pp.63.3-63.3
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    • 2016
  • We present the two-dimensional distribution of stellar populations in five E+A galaxies from GMOS-N/IFU spectroscopy (GN-2015B-Q-15). Numerical simulations demonstrated that E+A galaxies formed by major mergers contain young stellar populations (e.g. A-type stars) that are centrally-concentrated within scales of 1 kpc. However, several IFU studies reported that A-type stars are widely distributed on ${\gg}$ 1kpc scales. In contrast, Pracy et al. (2013) found a central concentration of A-stars and strong negative Balmer absorption line gradients within 1 kpc scales for local (z < 0.03) E+A galaxies. They claimed that previous studies failed to detect the central concentration because the E+A galaxy samples in previous studies are too far (z ~ 0.1) to resolve the central kpc scales. To verify Pracy et al.'s argument and the expectation from simulations, we selected five E+A galaxies at 0.03 < z < 0.05. Furthermore, we selected the targets in the mid-infrared green valley (Lee et al. 2015). Thanks to good seeing (${\sim}0.4^{{\prime}{\prime}}{\simeq}0.33kpc$) of our observation, we are able to resolve the central 1 kpc region of our targets. We found that all five galaxies have negative Balmer line gradients, but that three galaxies have flatter gradients than those reported in Pracy et al. We discuss the results in relation with galaxy merger history.

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Optical Properties of Mid-infrared Transparent ZnS Ceramics with Different Molar Ratio of S/Zn (S/Zn의 몰비에 따른 중적외선 투과용 ZnS 세라믹스의 소결과 광학적 특성)

  • Yeo, Seo-Yeong;Park, Buem-Keun;Kim, Chang-Il;Paik, Jong-Hoo
    • Journal of Sensor Science and Technology
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    • v.28 no.4
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    • pp.256-261
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    • 2019
  • In this study, mid-infrared transparent zinc sulfide (ZnS) ceramics were fabricated through hydrothermal synthesis with different molar ratios of S/Zn (S/Zn = 0.8, 1.0, 1.2, 1.4, and 1.6). The ZnS ceramics were sintered at a relatively low temperature of $850^{\circ}C$ to prevent the occurrence of the hexagonal phase featuring optical anisotropy. The phase composition, microstructure, and optical properties of the ZnS ceramics were subsequently investigated by employing X-ray diffraction, scanning electron microscopy, and Fouriertransform infrared spectroscopy. The results obtained indicate that the ZnS nanoparticles feature the cubic phase, without the hexagonal phase. Moreover, with increasing S, the crystallinity and particle size of the ZnS nanoparticles increased. The crystallinity and density of the ZnS ceramics improved when the molar ratio of S was higher than the molar ratio of Zn, thereby enhancing the transmittance. Furthermore, the ZnS ceramic with an S/Zn value of 1.2 was found to exhibit the highest transmittance of approximately 69% owing to the reduced occurrence of the hexagonal phase and a high density of 99.8%.

A study on the identification of turquoise by FT-IR (FT-IR을 이용한 터키석의 감별에 관한 연구)

  • Kim Young-Chool
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.14 no.6
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    • pp.272-276
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    • 2004
  • Inorganic materials, including gemstones, also have characteristic vibrational energies in the infrared that can be used for identification. For infrared spectroscopy, absorptions associated with the vibrations of the crystal structure (lattice vibrations) are characteristic of the given combination of atoms constituting the gemstone. Natural turquoise $CuAl_6(PO_4)_4\cdot(OH)_8\cdot 5H_2O$ can be distinguished easily from its common substitutes in the infrared range 2000~450$\textrm{cm}^{-1}$ by features in the mid-infrared. Gilson turquoise, which is a synthetic, exhibits a significantly smoother pattern when compared with natural turquoise, because of a different state of aggregation. Also, because the natural turquoise and gibbsite are so different chemically, their patterns are very different. The technique, which is infrared spectroscopy, is nondestructive and, with Fourier transform instrumentation, extremely rapid.

AKARI INFRARED CAMERA SURVEY OF THE LARGE MAGELLANIC CLOUD

  • Shimonishi, T.;Kato, D.;Ita, Y.;Onaka, T.;AKARI/IRC LMC team
    • Publications of The Korean Astronomical Society
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    • v.32 no.1
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    • pp.83-85
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    • 2017
  • We conducted an unbiased near- to mid-infrared imaging and spectroscopic survey of the Large Magellanic Cloud (LMC) as a part of the AKARI Mission Program "Large-area Survey of the LMC" (LSLMC, PI: T. Onaka). An area of about 10 square degrees of the LMC was observed by five photometric bands (3.2, 7, 11, 15, and $24{\mu}m$) and a low-resolution slitless prism ($2-5{\mu}m$, R ~20) equipped with AKARI /IRC. We constructed and publicly released photometric and spectroscopic catalogues of point sources in the LMC based on the survey data. The catalogues provide a large number of near-infrared spectral data, coupled with complementary broadband photometric data. Combined use of the present AKARI LSLMC catalogues with other infrared point source catalogues of the LMC possesses scientific potential that can be applied to various astronomical studies.

Proposed Science Programs for SPICA Near-Infrared Instrument

  • Jeong, Woong-Seob;Matsumoto, Toshio;Lee, Hyung-Mok;Koo, Bon-Chul;Im, Myung-Shin;Lee, Dae-Hee;Ree, Chang-Hee;Park, Young-Sik;Moon, Bong-Kon;Park, Sung-Joon;Pyo, Jeong-Hyun;Cha, Sang-Mok;SPICA-FPCTeam, SPICA-FPCTeam
    • The Bulletin of The Korean Astronomical Society
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    • v.35 no.2
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    • pp.56.2-56.2
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    • 2010
  • The SPICA (SPace Infrared Telescope for Cosmology & Astrophysics) project is a next-generation astronomical mission optimized for mid- and far-infrared observation with a cryogenically cooled 3m-class telescope. Due to its high angular resolution and unprecedented sensitivity, SPICA will enable us to resolve many key issues in the present-day astronomy. As an international collaboration, KASI proposed the near-infrared instrument which is composed of two parts; (1) science observation with the capability of imaging and spectroscopy covering $0.7{\mu}m$ to $5{\mu}m$ (FPC-S) (2) fine guiding to stabilize and improve the attitude (FPC-G). Here, we introduce the science programs proposed for SPICA/FPC-S.

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Characteristic comparison analysis of the green tourmalines from Myanmar and other deposits (미얀마와 타산지 녹색 투어말린의 특성비교 분석)

  • Kim, Kyung-Jin;Chung, Chae-Min;Ahn, Yong-Kil
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.1
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    • pp.39-46
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    • 2014
  • The green tourmalines from Kayah state, Myanmar were investigated by WD X-ray fluorescence, UV-vis, and mid-infrared spectroscopy for comparison to tourmalines of other deposits. The group of tourmaline was calculated and classified by chemical analysis. The samples belonged to the Calcic group and Uvite. The green tourmalines showed a strong absorption band at 415 and 611 nm. The presence of $V^{3+}$ ions is responsible for these absorption bands. Combination of the stretching and bending mode by the vibration between cationic and hydroxyl units (metal-OH) are observed in the 4600 ~ 4200 $cm^{-1}$.

Feasibility of Analyzing Soil Organic Carbon Fractions using Mid-Infrared Spectroscopy (중적외선분광분석법을 이용한 토양 유기 탄소 분획 분석)

  • Hong, Seung-Gil;Shin, JoungDu;Park, Kwang-Lai;Lee, Sang-Beom;Kim, Jinho;Kim, Seok-Cheol;Shiedung, Henning;Amelung, Wulf
    • Journal of the Korea Organic Resources Recycling Association
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    • v.23 no.3
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    • pp.85-92
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    • 2015
  • For concerning the climate change issues, the carbon sequestration and importance of soil organic matter are receiving high attention. To evaluate carbon sequestration in soil is important to determine the soil organic carbon (SOC) fractions such as WESOC (Water extractable soil organic carbon), and $CO_2$ emission by soil microbial respiration. However, the analyses for those contents are time-consuming procedure. There were studied the feasibility of MIRS (Mid-Infrared Spectroscopy), which has short analysis time for determining the WESOC and an incubated carbon in this study. Oven-dried soils at $100^{\circ}C$ and $350^{\circ}C$ were scanned with MIRS and compared with the chemically analyzed WESOC and cumulative carbon dioxide generated during 30, 60, 90, and 120 days of incubation periods, respectively. It was observed that an optimized determination coefficient was 0.6937 between WESOC and untreated soil processed by spectrum vector normalization (SNV) and 0.8933 between cumulative $CO_2$ from 30 days incubation and soil dried at $350^{\circ}C$ after subtracting air-dried soil processed by 1st derivatives. Therefore, it was shown that Quantification of soil organic carbon fractions was possibility to be analyzed by using MIRS.

2 - 5 μm Spectroscopy of Red Point Sources in the Galactic Center

  • Jang, DaJeong;An, Deokkeun;Sellgren, Kris;Ramirez, Solange V.
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.67.4-67.4
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    • 2019
  • We present preliminary results of our long-term (2009-2017) observing campaign using the NASA IRTF at Mauna Kea, to obtain $2-5{\mu}m$ spectroscopy of ~200 red point sources in the line of sight to the Galactic center. Point sources in our sample were selected from the mid-infrared images of the Spitzer Space telescope, and include candidate massive young stellar objects, which have previously been identified from our Spitzer/IRS spectroscopy. We show high foreground extinction of these sources from deep $3.1{\mu}m$ H2O ice and aliphatic hydrocarbon absorption features, suggesting that they are likely located in the central 300 pc region of the Galactic center. While many sources reveal photospheric $2.3{\mu}m$ gas CO absorption, few of them clearly indicate $3.54{\mu}m$ CH3OH ice absorption, possibly indicating a large dust column density intrinsic to a massive young stellar object.

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Discrimination model for cultivation origin of paper mulberry bast fiber and Hanji based on NIR and MIR spectral data combined with PLS-DA (닥나무 인피섬유와 한지의 원산지 판별모델 개발을 위한 NIR 및 MIR 스펙트럼 데이터의 PLS-DA 적용)

  • Jang, Kyung-Ju;Jung, So-Yoon;Go, In-Hee;Jeong, Seon-Hwa
    • Analytical Science and Technology
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    • v.32 no.1
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    • pp.7-16
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    • 2019
  • The objective of this study was the development of a discrimination model for the cultivational origin of paper mulberry bast fiber and Hanji using near infrared (NIR) and mid infrared (MIR) spectroscopy combined with partial least squares discriminant analysis (PLS-DA). Paper mulberry bast fiber was purchased in 10 different regions of Korea, and used to make Hanji. PLS-DA was performed using pre-treated FT-NIR and FT-MIR spectral data for paper mulberry bast fiber and Hanji. PLS-DA of paper mulberry bast fiber and Hanji samples, using FT-NIR spectral data, showed 100 % performance in cross validation and the confusion matrix (accuracy, sensitivity, and specificity). The discrimination models showed four regional groups which demonstrated clearer separation and much superior score plots in the NIR spectral data-based model than in the MIR spectral data-based model. Furthermore, the discrimination model based on the NIR spectral data of paper mulberry bast fiber had highly similar score morphology to that of the discrimination model based on the NIR spectral data of Hanji.