• Title/Summary/Keyword: Extinction Spectrum

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Theoretical Study on the Effects of Particle Size Distribution on the Optical Properties of Colloidal Gold (입자 크기 분포가 금 콜로이드의 광학성질에 미치는 영향에 대한 이론 연구)

  • Kim, Hyo-Jeong;Saha Leton Chandra;Jang, Joon-Kyung
    • Journal of the Korean Chemical Society
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    • v.51 no.5
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    • pp.407-411
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    • 2007
  • Mie theory has been used to calculate the extinction of a gold nanoparticle in water by varying its diameter from 1 to 1000 nm. Utilizing this size-dependent theoretical spectrum, we have calculated the extinction spectrum of a colloidal gold by taking into account the size distribution of particle. Such calculation is in better agreement with experiment than the calculation without considering the size distribution. A least-squares fitting is used to deduce the size distribution from an experimental extinction spectrum. For particles with their diameters ranging from 10 to 28 nanometers, the fitting gives reasonable agreement with the size distribution obtained from tunneling electron microscope images.

Discrete Dipole Approximation Calculation of the Extinction Spectra of Gold-Silver Alloy Nanoparticles (이산 쌍극자 근사를 이용한 금-은 합금 나노입자의 소광 스펙트럼 계산)

  • Lee, Hee-Mi;Chandra, Saha Leton;Jang, Joon-Kyung
    • Journal of the Korean Chemical Society
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    • v.51 no.2
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    • pp.136-140
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    • 2007
  • By using the discrete-dipole approximation, we computed the extinction spectrum of a gold-silver alloy nanoparticle. We have examined how the surface plasmon resonance changes with respect to the variation in the composition of the alloy particle. As the fraction of silver increases for a 10nm particle, the peak position of the extinction spectrum blue-shifts linearly. The intensity of the peak however increases exponentially with increasing the silver fraction. These results are in accord with the previous experimental results.

Analysis of Oxy- and Metmyoglobin in Beef Chuck by Absorption Spectrophotometer and Hunter-Lab (Hunter-Lab와 분광광도계(分光光度計)에 의한 쇠고기의 Oxy-와 Metmyoglobin의 분석(分析))

  • Yeo, Young Keun;Park, Choon Ran
    • Current Research on Agriculture and Life Sciences
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    • v.1
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    • pp.165-167
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    • 1983
  • Oxy - and metmyoglobin concentrations in beef chuck were measured by Hunter-Lab and spectrophotometer. The values of oxymyoglobin by Hunter-Lab got 34.03, 10.40, and 6.50 as average in L, a, and b while the CIE color primaries were 13.33, 11.58, and 9.94 in X, Y, and Z, respectively. The metmyoglobin values recorded 39.10, 13.20, and 10.13 in L, a, and b, of which values were converted to 17.88, 15.29, and 11.40 in X, Y, and Z of the CIE primaries. Absorption spectrum of oxymyoglobin showed 2 peaks which were 0.79 and 0.83 pf extinction coefficient with 530 and 570nm in wavelengh, and that of metmyoglobin appeared on an irregular curve with a summit of 0.58 and 500 in extinction coeffcient ($cm^2$/mg) and wavelength(nm) each.

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DETERMINATION OF ATMOSPHERIC EXTINCTION COEFFICIENT AT BOHYUNSAN OPTICAL ASTRONOMY OBSERVATORY (보현산 천문대의 대기 소광계수)

  • Kim, Kang-Min;Son, Dong-Hoon;Hyung, Siek;Yoon, Tae-Seog
    • Publications of The Korean Astronomical Society
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    • v.12 no.1
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    • pp.167-172
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    • 1997
  • Detailed low spectral resolution observations of the spectrum have been made for three early spectral type standard stars, HR718, HR1544, HR3454, respectively, for the wavelength region 4,300 A to 7,500 A, using the Bohyunsan Optical Astronomy Observatory (BOAO) Middle- Dispersion Spectrograph. These standard stars were chosen from well-known bright northern standard stars. All of the observed long slit spectral data has been reduced and analyzed using the IRAF reduction procedure. The derived extinction coefficients are compared with the other observatory result. The derived value can be used in the determination of flux calibration of BOAO spectroscopic observation. However, until the high quality data are secured from a new series of observation in the blue region and are re-analyzed together, the extinction coefficients below the 4,000 A wavelength remains unknown.

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A Study of Optical Characteristics for Biodiesel and Diesel Smoke Particles and Measuring their Dimensionless Light Extinction Constants (바이오디젤과 디젤 연기입자의 광학특성 및 무차원 광소멸계수 측정에 관한 연구)

  • Choi, Seuk-Cheun;Jang, Yeong-Seok;Park, Seul-Hyun;Kim, Youn-Kyu
    • Fire Science and Engineering
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    • v.30 no.1
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    • pp.37-42
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    • 2016
  • The dimensionless extinction constants of smoke particles produced from burning of soy methyl ester (B100) biodiesel and ultra low sulfur diesel (ULSD) fuels were measured. To this end, optical measurements of smoke volume fraction with the aid of a He-Ne laser at 633 nm were compared to the simultaneous gravimetric measurements. The average value of measured dimensionless extinction constants at 633 nm was 11.8 for biodiesel smoke particles and 11.1 for diesel smoke particles, respectively whose values are very comparable withing the range of measurement uncertainty (${\pm}10.1%$). The analysis of Raman spectroscopy revealed that overall characteristics of light extinction between particles produced from each fuel may differ from each other.

Study of Optical Transmission Performance in IP-over-WDM Networks Based on FSK/ASK Combined Modulation Format

  • Xiangjun, Xin;Andre, Paulo Sergio de Brito;Teixeira, Antonio Luis Jesus;Monteiro, Paulo P.;Rocha, Jose R. F. da
    • ETRI Journal
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    • v.27 no.3
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    • pp.267-272
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    • 2005
  • The transmission performance of optical labeling based on a combined frequency shift keying/amplitude shift keying (FSK/ASK) format is studied by numerical simulation. The simulation demonstrates that the bit-error ratio (BER) characteristic of an ASK signal is limited by the extinction ratio, received optical power, and dispersion, simultaneously. However, an FSK signal is mainly limited by the extinction ratio (ER) and received optical power when the peak spectrum, which is used to detect the FSK signal, is relatively narrow.

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Determination of the complex refractive index and thickness of MNA/PMMA thin film (MNA/PMMA 고분자박막의 복소굴절율 및 두께결정)

  • 김상열
    • Korean Journal of Optics and Photonics
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    • v.7 no.4
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    • pp.357-362
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    • 1996
  • The thickness and the spectrum of the complex refractive index in the region 1.5~4.5 eV, of an MNA/PMMA thin film fabricated by spin casting are determined. The film thickness and the refractive index in its transparent region is calculated by modeling the spectroscopic ellipsometry data. The extinction coefficient spectrum is obtained from the absorption spectrum in its non-transparent region. The best fit oscillator parameters of the classical Lorentz oscillator and a quantum mechanical oscillator are found. The complex refractive index spectrum by these oscillators are compared. The present technique can be applied to get the thickness and the complex refractive index of unknown polymer films and thus it will be useful in optical characterization of those films.

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A study on the optical properties of PLT thin films with varying the La concentration by using the transmission spectrum (투과곡선을 이용한 La 농도에 따른 PLT 박막의 광학적 특성에 관한 연구)

  • 강성준;윤석민;윤영섭
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.34D no.5
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    • pp.22-31
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    • 1997
  • We have measured the optical properties, thickness, and energy band gap of the P $b_{1-x}$/100/L $a_{x}$100/ $Ti_{1-}$0.25x/100/ $O_{3}$ (PLT(x)) thin film prepared by the sol-gel method with varying the La concentration, x, fyom 15 nto 33 mol%. We have obtained the values from the tranmission spectrum and employed the envelope method in anayzing the spectrum. We have also performed the simulation of the transmission spectrum on the PC (personal computer) to verify the accuracy of the values 15 to 33mol%, the refractive index (at .lambda.=632.8nm) increases from 2.39 to 2.44. The extinction coefficient does not depend on the la concentration but mainly on te wavelength, and has the values between 0.2 and 0.5 at the wavelength shorter than 330nm and between 0.001 and 0.008 at the wavelength longer than 700nm. The energy band gap of the PLT (x) thin film has been obtained on the assumption of the direct band-to-band transition. It decreases from 3.28 to 3.17eV as the La concentration increases from 15 to 33 mol%. The thickness of the PLT(x) thin film has been also obtained in high accuracy by the envelope method..

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The New Mass Estimator of Black Hole in Active Galaxies with Near Infrared Hydrogen Line

  • Kim, Do-Hyeong;Im, Myeong-Sin;Kim, Min-Jin
    • The Bulletin of The Korean Astronomical Society
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    • v.35 no.1
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    • pp.80-80
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    • 2010
  • About 50% of Active Galactic Nuclei(AGNs) are found to be red and dust-obscured. They are believed to be in an early dusty stage of AGNs evolution or affected by dust torus in the direction of line of sight. However, optical spectrum is affected by dust extinction, making it difficult to study their properties, such as FWHM and luminosity. In order to reveal the mass of central Black Hole(BH) in red AGN, we establish a new BH mass estimator for typical type1 AGNs using Near InfraRed(NIR) hydrogen line($P_{\alpha}$ and $P_{\beta}$), since these lines are at longer wavelength, less affected by dust extinction than optical hydrogen lines, such as $H_{\alpha}$ and $H_{\alpha}$. To derive the new empirical formula, we use a sample of well-known 36 AGN with a wide BH mass range of $10^6-10^9\;M_{\odot}$, where $M_{BH}s$ are estimated by reverberation mapping method and single epoch method. The $P_{\alpha}/P_{\beta}$ luminosities and FWHMs are derived by analyzing IRTF NIR spectra or taken from literature values. We show that luminosities and FWHMs of these lines correlate well with those of Balmer lines. Suggesting that Paschen and Balmer broad lines are originated from same region. Finally, we present the new $M_{BH}$ formula that are based on $P_{\alpha}/P_{\beta}$ luminosity and FWHM. We hope that our result will be used for investigating red AGNs.

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