• Publications of The Korean Astronomical Society
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• v.22 no.1
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• pp.21-33
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• 2007

Ever since the identification of 6830 and 7088 features as the Raman scattered O VI 1032, 1038 resonance doublets in symbiotic stars by Schmid (1989), Raman scattering by atomic hydrogen has been a very unique tool to investigate the mass transfer processes in symbiotic stars. Discovery of Raman scattered He II in young planetary nebulae (NGC 7027, NGC 6302, IC 5117) allow one to expect that Raman scattering can be an extremely useful tool to look into the mass loss processes in these objects. Because hydrogen is a single electron atom, their wavefunctions are known in closed form, so that exact calculations of cross sections are feasible. In this paper, I review some basic properties of Raman scattered features and present detailed and explicit matrix elements for computation of the scattering cross section of radiation with atomic hydrogen. Some astrophysical objects for which Raman scattering may be observationally pertinent are briefly mentioned.

• Advances in nano research
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• v.1 no.2
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• pp.111-124
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• 2013

Surface-enhanced Raman scattering (SERS) effect deals with the enhancement of the Raman scattering intensity by molecules in the presence of a nanostructured metallic surface. The first observation of surface-enhanced Raman spectra was in 1974, when Fleischmann and his group at the University of Southampton, reported the first high-quality Raman spectra of monolayer-adsorbed pyridine on an electrochemically roughened Ag electrode surface. Over the last thirty years, it has developed into a versatile spectroscopic and analytical technique due to the rapid and explosive progress of nanoscience and nanotechnology. This review article describes the recent development in field of surface-enhanced Raman scattering research, especially fabrication of various SERS active substrates, mechanism of SERS effect and its various applications in both surface sciences and analytical sciences.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.148.2-148.2
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• 2011

Many symbiotic stars exhibit features formed through Raman scattering with hydrogent atom, which can be useful in probing the mass loss and mass transfer processes. These include Raman scattered O VI 6830, 7088, Raman scattered He II 6545, 4850, 4332, and broad wings around Balmer emission lines. In this study we investigate the basic properties of broad Balmer wings formed through Raman scattering using a Monte Carlo technique. Special attention is made on the symmetry of the wings which is expected to be broken due to asymmetric scattering cross section. In this poster, we show preliminary results.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.50.2-50.2
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• 2010

We present the explicit expressions for the matrix elements associated with the interaction of photons with atomic hydrogen. These expressions are applied to compute the scattering cross section for the Raman scattering operating blueward of Lyman epsilon and H gamma. A brief discussion that re relevant to some symbiotic stars and young planetary nebulae is also presented.

• Journal of ILASS-Korea
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• v.2 no.4
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• pp.7-14
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• 1997

Laser Raman scattering method has been applied to measure equivalence ratio of methane/air mixture in injected spray. We used high power KrF excimer laser$(\lambda=248nm)$ and a high gain ICCD camera to capture low intensity signal. Raman shifts and Raman scattering cross -sections of $H_2,\;O_2,\;N_2,\;CO_2,\;CH_4\;and\;C_3H_8$ are measured precisely. Our results show an excellent agreement with those of other groups. Mole fraction measurement of $O_2\;and\;N_2$ from air shows that $O_2:N_2=0.206:0.794$. We used gas injector which was operated at 1 bar. Methane is used as a fuel. Spray region is $10mm\times37mm$ and this region is divided into 80 points. In Raman signals are obtained and ensemble averaged for each point. 3-d and contour plot of distribution of equuivalence ratio is presented. Our measured results show that the equivalence ratio of methane/air mixture in methane-rich region is reasonable. However, more study is necessary for methane-lean region because background noise level is almost same as Raman intensity of methane.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.86.4-87
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• 2017

Symbiotic stars are binary systems composed of a hot white dwarf and a mass losing giant. Many symbiotic stars are known to exhibit broad wings around Balmer emission line. We show high resolution spectra of S-type symbiotic stars, Z Andromedae and AG Draconis, obtained with the ESPaDOnS and the 3.6 m Canada-France-Hawaii Telescope, in which we find prominent broad wings around Balmer lines. We adopt Monte-Carlo technique to consider two types of wing formation mechanisms, which are Thomson scattering by free electron in H II region and Raman scattering by atomic hydrogen in H I region. We find that Thomson wings of $H{\alpha}$ and $H{\beta}$ have the same widths in the Doppler space due to the cross section independent of wavelength. In contrast, Raman $H{\alpha}$ wings are 3 times broader widths than $H{\beta}$ counterparts, which is attributed to the different cross sections and branching ratios. Our CFHT data show that $H{\alpha}$ wings of Z Andromedae and AG Draconis are broader than $H{\beta}$ wings, lending strong support to the Raman scattering origin of Balmer wings in these objects.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.470-474
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• 2013

Surfaced-enhanced Raman scattering (SERS) of 4,4'-biphenyldithiol (BPDT) has been investigated at a silver island film. Ordinary Raman (OR) spectra of neat sample in solid state and in basic solution have also been taken for comparison. The spectral feature in the SERS spectrum was similar to that for the OR spectrum in basic solution, except for the broadening of ring stretching bands indicative of the presence of surface-phenyl ring $\pi$ interaction. In contrast, only absence of the C-H stretching band with very small Raman scattering cross-section seemed not pertinent in judging the definitive orientation of molecule. The observed vibrational bands in the SERS spectrum have been assigned by referring to the normal modes and wavenumbers from density functional theory (DFT) calculations of the simple model as 4,4'-biphenyldithiolates bound to two Ag atoms at the both ends. Excellent agreement between the experimental and the calculated results was achieved, which is remarkable considering the level of theory applied.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.79.1-79.1
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• 2012

Due to the quantum interference of many atomic levels, the exact scattering cross section around a given resonance transition deviates from the Lorentz function when the frequency of the incident radiation is quite far from the resonance frequency. This atomic effect is quite significant in the case of damped Ly alpha systems, where HI column density is in excess of 10^20 cm^-2. In this poster, we present the deviation quantitatively taking into consideration of the Rayleigh and Raman scattering around Lyman alpha and Lyman beta.

• Journal of Korean Vacuum Science & Technology
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• v.6 no.2
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• pp.71-75
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• 2002

GaAs polycrystalline thin films with good performance were prepared on conducting glass by hot wall epitaxy (HWE), which were used for solar cell. Electron probe micro-analyzer (EPMA) was applied for the composition, morphology of surface and cross-section of grown films, and X-ray diffraction (XRD) for their phase structure; Raman scattering spectum (RSS) and photoluminescence (PL) were used for evaluating their optical characteristics. The results show that, there is textured structure on the surface of grown GaAs polycrystalline films, which is greatly promised to be suitable for the candidate of solar cell with low cost and high efficiency. It is concluded that the source and substrate at temperature of 900 ~ 930 $\^{C}$ and 500 $\^{C}$ respectively would be beneficial for such films.