• Title/Summary/Keyword: raman

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The Effect of Laser on Silicon thin film measurement in Raman spectroscopy

  • Lee, Yeong-Ju;Park, Seong-Gyu;Gwon, Jeong-Dae;Kim, Dong-Ho;Jeong, Yong-Su
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2012.05a
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    • pp.249-250
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    • 2012
  • Raman spectroscopy는 미세결정질 실리콘 박막의 분석에 널리 사용되고 있으며 특히, 측정 자료를 통해 미세결정질 분율을 알아낼 수 있다. Raman 측정 시 조사되는 laser의 특성에 따라 박막시편 측정값에 일련의 변화가 나타나는 것을 알 수 있었다.

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Tip-Enhanced Raman Scattering with a Nanoparticle-Functionalized Probe

  • Park, Chan-Gyu;Kim, Ju-Young;Lee, Eun-Byoul;Choi, Han-Kyu;Park, Won-Hwa;Kim, Jin-Wook;Kim, Zee-Hwan
    • Bulletin of the Korean Chemical Society
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    • v.33 no.5
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    • pp.1748-1752
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    • 2012
  • We carried out the tip-enhanced Raman scattering (TERS) with a tip that is functionalized with a Aunanoparticle (AuNP, with a diameter of 250 nm). The AuNP tip is fabricated by a direct mechanical pickup of a AuNP from a flat substrate, and the TERS signal from the AuNP tip - organic monolayer - Au thin film (thickness of 10 nm) is recorded. We find that such a AuNP-tip interacting with a thin film routinely yields signal enhancement larger than ${\sim}10^4$, which is sufficient not only for local (with detection area of ~200 $nm^2$) Raman spectroscopy, but also the nanometric imaging of organic monolayers within a reasonable acquisition time (~20 minutes/image).

O VI Raman spectroscopy of the S-type symbiotic star V455 Sco

  • Heo, Jeong-Eun;Lee, Hee-Won;Lee, Ho-Gyu
    • The Bulletin of The Korean Astronomical Society
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    • v.40 no.1
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    • pp.90.2-90.2
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    • 2015
  • We present the high-resolution spectrum of the S-type symbiotic star V455 Sco obtained with the Dupont telescope in 2014 June. We note that the Raman-scattered O VI ${\lambda}1032$ at $6825{\AA}$ exhibits a triple-peak profile. Adopting an accretion disk model with an additional contribution from a collimated bipolar outflow, we attempt to fit the profile. We propose that the blue and central peaks are formed via Raman-scattering of O VI line photons from the accretion flow and that the bipolar flow is responsible for the remaining red peak. It is also noted that V455 Sco exhibits the Raman-scattered He II features blueward of $H{\alpha}$ and $H{\beta}$.

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Preparation and Characterization of Silica-coated Gold Nanoflowers (AuNFs) with Raman Dye Encoding

  • Yoo, Jihye;Lee, Sang-Wha
    • Bulletin of the Korean Chemical Society
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    • v.35 no.9
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    • pp.2765-2768
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    • 2014
  • Flower-like Au nanoparticles, so-called Au nanoflowers (AuNFs), were synthesized by simply adding ascorbic acid to a gold acid solution in the presence of a chitosan biopolymer. The chitosan-entangled AuNFs exhibited strong plasmon absorption in the near-infrared (NIR) wavelength due to the aggregation of primary Au nanoparticles. The chitosan-entangled AuNFs were preferentially adsorbed by Raman-active 2-chlorothiophenol (CTP) molecules, and the CTP-encoded AuNFs (AuNF-CTPs) were subsequently coated with a thin silica layer by a sol-gel reaction with Si alkoxides. The silica-coated AuNFs (AuNF-CTPs@silica) exhibited the distinct Raman signals of adsorbed CTP molecules, as a potential nanoprobe with surface-enhanced Raman scattering (SERS).

Retrieval of Lidar Overlap Factor using Raman Lidar System (라만 라이다 시스템을 이용한 라이다 중첩함수 산출)

  • Noh, Young-M.;Muller, Detlef;Shin, Dong-Ho;Lee, Kyung-Hwa
    • Journal of Korean Society for Atmospheric Environment
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    • v.25 no.5
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    • pp.450-458
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    • 2009
  • The range-dependent overlap factor of a lidar system can be determined experimentally if a Raman backscatter signal by molecule is measured in addition to the usually observed elastic backscatter signal, which consists of a molecular component and a particle component. The direct determination of the overlap profile is presented and applied to a lidar measurement according to variation of telescope field-of-view and distance between telescope and transmitting laser. The retrieval of extinction coefficient by Raman method can generate high errors for heights below planetary boundary layer if the overlap effect is ignored. The overlap correction method presented here has been successfully applied to experimental data obtained in Gwangju, Korea.

The Effect of Induced Multipoles on the Fifth-order Raman Response

  • Jansen, Thomas I.C.;Duppen, Koos;Snijders, Jaap G.
    • Bulletin of the Korean Chemical Society
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    • v.24 no.8
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    • pp.1102-1106
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    • 2003
  • In our previous work we developed the Finite Field method in order to calculate the fifth-order Raman response. The method was applied to calculate various polarization components of the two-dimensional response of liquid $CS_2$. So far, all calculations relied on the dipole-induced dipole. Accurate time-dependent density functional theory calculations have shown that this model has big discrepancies, when molecules are close together as in the liquid. We now report results of investigations on the importance of multipole and electron overlap effects on the polarizability and the fifth-order Raman response. It is shown that these collision effects, especially the induced multipoles, are crucial in the description of the fifth-order response. The impact is found to be especially pronounced for the χ_{mmzzzz}^{(5)}$response that is solely due to interaction induced effects. The calculated response will be compared with various experimental results.

Evolution of stokes pulses of stimulated Raman scattering in a CeO$_2$-doped multimode fiber (GeO$_2$ 첨가 다중모드 광파이버에서 유도라만산란에 의한 스토크스 펄스 발생)

  • Yi, Yong-Woo;Hwang, In-Duck
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.6 no.7
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    • pp.1095-1099
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    • 2002
  • We experimentally investigate the evolution of nanosecond Stokes pulses in a single-pass Raman laser pumped by a Q-switched Nd:YAG laser at 1064 na As a Raman medium, a GeO2-doped graded-index multimode fiber ot 220 m long Is used. We demonstrate that efficient generation of several Stokes components with 1.5∼2.7 nanosecond pulsewidth is obtained by varying the input pump energy.

고온초전도체 $Y_{1-x}Ho_{x}Ba_{2}O_{7-y}$의 초전도성에 관한 연구

  • 김채옥;김재욱;김의훈;나훈균
    • Proceedings of the Materials Research Society of Korea Conference
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    • 1992.05b
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    • pp.102-106
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    • 1992
  • 고온 초전도체 $Y_{1-x}$Ho$_{x}$Ba$_2$O$_{7-y}$에서 대신 Ho를 치환시킨 시료를 제작하여 수송 임계전류밀도를 측정하였으며, 적외선 투과율과 Raman 스펙트럼 측정을 상온에서 실시하였다. 특히 Raman 측정은 수직으로 편광한 경우와 수평으로 편광한 경우를 비교하였다. 치환량의 변화에 따른 수송 임계전류밀도 값은 110-217 A/$\textrm{cm}^2$ 범위에 있었고 자기장이증가 됨에 따라 감소됨을 알수 있었다. 적외선 투과율과 Raman 스펙트럼 측정으로부터 얻은 Cu(1)-O(4) stretching mode는 초전도체의 결정 구조를 좌우하며 산소의 영향에 강한 영향을 받는다. 또한 이것은 치환양이 증가됨에 따라 감소하는 경향을 보였다. Raman 스펙트럼에서 수직 편광한 경우와 수평 편광한 경우 모두 asymmetric 한 형태를 이루었다. 특히 수평 편광한 경우는 BaCuO$_2$ phase 의 강도가 증가했다.다.했다.

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