• Korean Journal of Crystallography
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• v.7 no.1
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• pp.88-93
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• 1996

The multiplicity factor, which is defined as the number of different planes in a form having identical interplanar spacing and identical intensity, is tabulated here for the 21 noncentrosymmetric point groups on the basis of their symmetries.

• Korean Journal of Crystallography
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• v.6 no.1
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• pp.56-62
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• 1995

The thirty two point groups consist of eleven Laue groups (centrosymmetric point groups) and twenty one noncentrosymmteric point groups. In this paper, the reciprocal lattice points equivalent under the operations of 21 noncentrosymmetric point groups are derived.

• Journal of the Korean Vacuum Society
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• v.7 no.s1
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• pp.149-155
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• 1998

The linear electro-optic (EO) effect is one of the second-order nonlinear optical effects existing in a noncentrosymmetric macroscopic system. In a polymer thin film, the noncentrosymmetry is achieved by electric field poling. The magnitude of the linear EO response is determined through the orientational distribution function of hyperpolarizable molecular dipoles. The relation between the linear EO coefficient and the second-order nonlinear optical susceptibility is explained. Three different methods of measuring the linear EO coefficient of a poled nonliner optical polymer thin film are introduced and discussed. All of them make use of the interferometric technique, the difference being in the optical parameters which are interfering.

• Bulletin of the Korean Chemical Society
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• v.29 no.11
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• pp.2273-2276
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• 2008

• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2423-2426
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• 2012

• Molecules and Cells
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• v.26 no.6
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• pp.530-535
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• 2008

Optical signals based on Raman scattering, coherent anti-Stokes Raman scattering (CARS), and harmonic generation can be used to image biological molecules in living cells without labeling. Both Raman scattering and CARS signals can be used to detect frequencies of molecular vibrations and to obtain the molecular distributions in samples. Second-harmonic optical signals can also be generated in structured arrays of noncentrosymmetric molecules and can be used to detect structured aggregates of proteins, such as, collagen, myosin and tubulin. Since labeling techniques using chemical and biological reactions may cause undesirable changes in the sample, label-free molecular imaging techniques are essential for observation of living samples.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.2
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• pp.166-176
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• 1996

The fundamental conditions for growing $CsLiB_{6}O_{10}$ crystal, new nonlinear optical material, were investigated. Stoichiometirc mixture of $CsLiB_{6}O_{10}$ composition resulted in the crystal of the same composition in the process of heating at the temperature above $600^{\circ}C$. No phase transition was observed in the $CsLiB_{6}O_{10}$ crystal in the temperature range of $600^{\circ}C~800^{\circ}C$, and $CsLiB_{6}O_{10}$ crystal melted congruently at $850^{\circ}C$. When the melt of this composition was cooled at rates of $1~150^{\circ}C/hr$, glass state ingot was formed regardless of cooling rates. However, $CsLiB_{6}O_{10}$ crystals were formed directly from the melt at any cooling rate in the presence of $CsLiB_{6}O_{10}$ seed crystal in the melt. Transparent $CsLiB_{6}O_{10}$ single crystal was grown from the melt using the seed crystal at the growing rate of 0.06 mm/hr in the furnace having the temperature gradient of $100^{\circ}C/cm$. Analysis of the single crystal showed that the crystal belonged to the noncentrosymmetric tetragonal space group 142d and unit cell dimensions were $a=10.467(1)\;{\AA},\;c=8.972(1)\;{\AA}\;and\;V=983.0(2)\;{\AA}^3$. Optical absorption edge of the crystal was observed at 180mm and the crystal showed a good optical transparency (70% transmittance, sample thickness 0.5 mm) in the wide wavelength range above 300 nm.

• Applied Chemistry for Engineering
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• v.28 no.3
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• pp.290-293
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• 2017

In this study, the fundamental behavior of microdomains in block copolymer/nanoparticle composite thin films was examined. In this experiment, polystyrene-b-poly(2-vinylpyridine) block copolymer and CdSe nanoparticles having a noncentrosymmetric property were employed. Composite hybrid thin films were produced by a spin coating method, and changes in the internal structure of composite thin films were monitored mainly by transmission electron microscopy. In summary, nanoparticles resided inside the thin film relatively intact, however, the block copolymer microdomains rotated parallel to the electric field direction. This study will be very helpful for future research activities regarding behaviors of heterogeneous composite materials under external fields.

• Korean Journal of Crystallography
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• v.11 no.2
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• pp.89-94
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• 2000

A crystallographic unit cell can be transformed into another one by a 3×3 transformantion matrix. If the determinant of the transformation matrix has a negative value, the newly transformed unit cell becomes a left-handed cell. The best way of transforming the left-handed cell to the right-handed one is to multiply each element of the transformation matrix by-1, and its corresponding transformation matrix must be applied tot he atomic coordinates of a noncentrosymmetric crystal so as to maintain the absolute configuration unchanged. The behaviour of absolute configuration caused by transforming the crystallographic unit cell was examined theoretically and experimentally on the compound (S)-(+)-4-phenyl-1-[4-aminobenzoyl) indoline-5-sulfonyl]-4,5-dihydro-2-imidazolone hydrochloride.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.225-227
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• 1994

The second-order nonlinear optical effect, especially the second harmonic generation, in Langmuir-Blodgett(LB) films have get much attention over the past few years. For second harmonic generation(SHG) of the ultrathin organic films, the multilayer structure of the film should have the noncentrosymmetric arrangements of molecules. The Langmuir-Blodgett technique can result in the production of thin films of precisely controlled dimensions and structure. In this paper, n-octadecyl 4-(4'-nitrophenylazo)-1-naphthyl ether, ONNE(azohenzene derivative), was synthesized and the optical properties of ONNE was studied. Nonccntrosymmctric Z-type LB films of ONNE were prepared and SHG intensity of the film were measured. The structural characteristics of floating monolayer(L film) and LB film of ONNE were discussed with $\pi$-A isotherm. UV-visible absorption spectroscopy and spectroscopic ellipsometry. The polarized UV-visible absorption spectroscopy and SHO intensity suggest the molecular orientation in LB film.