• Bulletin of the Korean Chemical Society
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• v.17 no.1
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• pp.69-72
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• 1996

The NMR dipolar shift in tetrahedral and tetragonally-distorted tetrahedral complexes for Cu(Ⅱ) has been calculated adopting nonmultipole expansion method. The exact solution of ΔB/B(ppm) is exactly in agreement with multipolar results when R, the distance between the paramagnetic ion and the nucleus, is larger than 0.2 nm. The major contribution to the dipolar shift arises from 1/R3 term but the other terms, 1/R5 and 1/R7, contribute significantly to the pseudocontact shift when R is shorter than 0.5 nm. The shift is mainly due to the 3d orbitals and sensitive to distortion parameters at short range of R.

• Journal of Biomedical Engineering Research
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• v.31 no.5
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• pp.412-416
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• 2010

In this study, we measured the chemical shift change of metabolite peaks in the brain-metabolite phantom according to the temperature variation using nuclear magnetic resonance(NMR). The temperature range in NMR system was controled from 25 to 80 (5 step) by internal temperature controller. Temperature coefficients of each metabolite peaks were also calculated from the measured chemical shift depending on the temperature. The chemical shift changes depending on temperature were validated by linear regression method for each metabolite peaks. The temperature coefficients of $_{tot}Cr$, Cho, Cr, NAA, and Lac were 0.0086, 0.0088, 0.0091, 0.0089, and 0.0088ppm/$^{\circ}C$, respectively. This study shows that chemical shift change of brain metabolite and temperature variation have linear relationship each other. This also makes authors believe that brain temperature measurement is possible using MR spectroscopic imaging technique.

• Journal of the Korean Chemical Society
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• v.17 no.4
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• pp.240-246
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• 1973

An analytic expression for the intensity of collision-induced light scattering obstained by introducing both short-range and long-range effects on the induced anisotropy. By taking argon as a specific example, it is shown that a narrow band at small frequency shifts is caused by long-range effects, while a broad band in the far wing of the spectrum is due to short-range effects. The overall intensity is a synthesis of these two bands and does not follow a simple exponential form. As temperature increases, the intensity at large frequency shifts increases makedly, while at small frequency shifts it changes little.

• Korean Journal of Pharmacognosy
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• v.8 no.1
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• pp.23-29
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• 1977

The $^{13}C-chemical\;shifts$ of the phenolic coumarine derivatives, aesculetin, daphnetin and herniarin were studied on the basis of my previous report. All spectral data found in this report could be utilized to the structure elucidation of the unknown phenolic coumarine derivatives and other phenolic compounds. In addition, it is suggested that a long range coupling may occur in the following structure as represented by arrow.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12
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• pp.1091-1096
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• 2003

Ion implantation in polymeric materials can induce dramatic chemical modifications, such as bond breaking, cross linking, formation of new chemical products, which have strong influences on the macroscopic properties of the materials. In this study ion implantation was performed onto polymer, PC(polycarbonate), in order to investigate change of the optical transmittance property focusing ultraviolet ray range(200-400nm). PC was irradiated with N, Ar, Kr, Xe ions at the ion energy of 50keV and the dose range of 5 ${\times}$ 10$\^$15/, 1 ${\times}$ 10$\^$16/, 7${\times}$10$\^$16/ ions/$\textrm{cm}^2$. FT-IR, XPS, UV/Vis transmittance spectroscopy measurement technologies were employed to obtain chemical. structural properties and optical transmittance of irradiated polymer. The original PC(unimplanted) is quite transparent that it has more than 88% transmittance in the range UV-A(320∼400nm), but after ion implantation, surface colors were changed to the dark brown and the transmittance of UV ray decreased for all implantation condition, and the absorption edge was shift to visible range with increasing mass of implanted ion species and dose.

• Journal of the Korean Chemical Society
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• v.40 no.10
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• pp.656-662
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• 1996

Using low temperature and atmospheric pressure method, we synthesized Na, TPA-ZSM-5 with Si/Al ratio of about 100. We employed 27Al and 29Si MAS NMR spectroscopy and FT-IR to investigate the crystallization process as a function of time. The chemical shift depends on the initial composition of reactants and changes during the course of synthesis different from those reported by others earlier. However, the chemical shift of our final product showed in the range of typical ZSM-5. And the defect site was removed by the calcine. From XRD and SEM data, the formation of ZSM-5 was also confirmed.

• Bulletin of the Korean Chemical Society
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• v.23 no.11
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• pp.1513-1518
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• 2002

Kinetic studies on the water-gas shift reaction catalyzed by magnetite/chromium oxide and copper/zinc oxide were carried out by using an in situ photoacoustic spectroscopic technique. The reactions were performed in a closed-circulation reactor system using a differential photoacoustic cell at total pressure of 40 Torr in the temperature range of 100 to $350^{\circ}C.$ The CO2 photoacoustic signal varying with the concentration of CO2 during the catalytic reaction was recorded as a function of time. The time-resolved photoacoustic spectra obtained for the initial reaction stage provided precise data of CO2 formation rate. The apparent activation energies determined from the initial rates were 74.7 kJ/mol for the magnetite/chromium oxide catalyst and 50.9 kJ/mol for the copper/zinc oxide catalyst. To determine the reaction orders, partial pressures of CO(g) and H2O(g) in the reaction mixture were varied at a constant total pressure of 40 Torr with N2 buffer gas. For the magnetite/chromium oxide catalyst, the reaction orders with respect to CO and H2O were determined to be 0.93 and 0.18, respectively. For the copper/zinc oxide catalyst, the reaction orders with respect to CO and H2O were determined to be 0.79 and 0, respectively.

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.351-359
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• 1992

Interaction of xenon with alkaline-earth cations in Y zeolite supercage was studied by xenon adsorption and $^{129}Xe$ NMR experiments. The CaY and the BaY samples were prepared by exchanging $Ca^{2+}$ and $Ba^{2+}$ into a high-purity NaY zeolite. Xenon adsorption isotherms of these samples were obtained by using a conventional volummetric gas adsorption apparatus in the range of 260 to 320 K and the chemical shift in the $^{129}Xe$ NMR spectrum of the adsorbed xenon was measured at 296 K. The chemical shift against pressure was quantitatively explained assuming that the xenon gas exchanged very rapidly between various adsorption sites consisting of zeolite-framework surface and alkaline-earth ion. From this analysis, it was found that the alkaline-earth ion adsorbed xenon more strongly than $Na^+$ ion and zeolite-framework surface. Baring on the difference of the adsorption strength, the number of the alkaline-earth cations present in the zeolite supercage could be estimated by analyzing the adsorption isotherm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.738-739
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• 2008

The SiOC film of carbon centered system was prepared using bistrimethylsilymethane and oxygen mixed precursor by the chemical vapor deposition. The chemical properties of he SiOC film were analyzed by the contact angle and FTIR spectra. The dielectric constant of the deposited films decreased after annealing process, and the correlation between the increasing the BTMSM/O2 flow rate ratio and he dielectric constant did not exist. However, the trend of increasing or decreasing of the dielectric constant repeated and here is the correlation ship between the dielectric constant and the Si-O-C bond in the range of $950{\sim}1200\;cm^{-1}$. The dielectric constant decreased between samples with the chemical shift. The lowest dielectric constant was 1.65 at the sample, which was observed he chemical shift.

• Journal of the Korean Vacuum Society
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• v.17 no.4
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• pp.341-345
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• 2008

The SiOC film of carbon centered system was prepared using bistrimethylsilylmethane and oxygen mixed precursor by the chemical vapor deposition. The chemical properties of the SiOC film were analyzed by the contact anlge and FTIR spectra. The dielectric constant of the deposited films decreased after annealing process, and the correlation between the increasing the BTMSM/$O_2$ flow rate ratio and the dielectric constant did not exist. However, the trend of increasing or decreasing of the dielectric constant repeated and there is the correlation ship between the dielectric constant and the Si-O-C bond in the range of $950{\sim}1200\;cm^{-1}$. The dielectric constant decreased between samples with the chemical shift. The lowest dielectric constant was 1.65 at the sample, which was observed the chemical shift.