• Journal of the Korean Chemical Society
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• v.54 no.6
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• pp.799-808
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• 2010

In this study, we conducted a textbook analysis and a conceptual test in order to investigate misconceptions of preservice chemistry teachers in understanding motions of molecular gases. As a result, we found out that many of the general chemistry textbooks not only introduce motions of molecular gases by explaining basic conceptions and using simple models, but also omit the explanation on center of mass when dealing with rotational motion. The physical chemistry textbooks, however, mainly approach motions of molecular gases in terms of spectroscopy and use various models to explain more intensified concepts, referring the center of mass in rotational motions. Meanwhile, pre-service chemistry teachers' confidence and understanding in the motions of molecular gases were very low and pre-service teachers also had many misconceptions about them. We believe this is because they had a tendency to depend largely on their intuition based on the pre-conceptions and the visual materials in the textbooks.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.4-5
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• 2010

The surface phonon is defined as a coherent vibrational excitation of surface atoms propagating along the surface. It is characterized by a phonon dispersion curves, which were extensively studied in 1990's using helium atom scattering and high-resolution electron-energy-loss spectroscopy (HREELS)[1].The understanding is mainly based on the theoretical framework of a classical bond model or cluster calculations. The recent sample preparation and first principles calculations open the naval way to deep insight for surface phonon problems. The surface phonon dispersion on the hydrogen-terminated Si(111)-($1{\times}1$) surface [H:Si(111)] is the typical system and already reported experimentally [2] and theoretically [3], although the understandingis incomplete. The sample contaminated by the oxygen atoms on the surface and the calculations were also classical. In this study, firstly, we have prepared an ultra-clean H:Si(111) surface [4] and measured the surface phonon dispersion curvesusing HREELS. Secondly, we have performed first-principles density functional calculations with the projector augmented wave functionals, as implemented in VASP, using generalized gradient approximations. We used aslab of six silicon layers and both top and bottom surfaces were terminated with hydrogen atoms. Finally, we have compared with the surface phonon dispersion of deuterium-terminatedSi(111)-($1{\times}1$) surface[5] and led to our conclusions. The Si-H stretching and the bending modes are observed at 258.5 and 78.2 meV, respectively. These energies are the same as the previously reported values [2], but the energy-loss peaks at the lower energy regions are dramatically shifted. Through this combination study, we have formulated the procedure of preparing ultra-clean H:Si(111)/D:Si(111), which was confirmed by HREELS vibrational analysis. The Si surface will be utilized for further nano-physics research as well as for the materials for nano-fubrication.

• Journal of the Mineralogical Society of Korea
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• v.24 no.4
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• pp.289-300
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• 2011

Atomistic origins of carbon solubility into silicates are essential to understand the effect of carbon on the properties of silicates and evolution of the Earth system through igneous and volcanic processes. Here, we investigate the atomic structure and NMR properties of dissolved carbon in enstatite using Raman spectroscopy and quantum chemical calculations. Raman spectrum for enstatite synthesized with 2.4. wt% of amorphous carbon at 1.5 GPa and $1,400^{\circ}C$ shows vibrational modes of enstatite, but does not show any vibrational modes of $CO_2$ or ${CO_3}^{2-}$. The result indicates low solubility of carbon into enstatite at a given pressure and temperature conditions. Because $^{13}C$ NMR chemical shift is sensitive to local atomic structure around carbon and we calculated $^{13}C$ NMR chemical shielding tensors for C substituted enstatite cluster as well as molecular $CO_2$ using quantum chemical calculations to give insights into $^{13}C$ NMR chemical shifts of carbon in enstatite. The result shows that $^{13}C$ NMR chemical shift of $CO_2$ is 125 ppm, consistent with previous studies. Calculated $^{13}C$ NMR chemical shift of C is ~254 ppm. The current calculation will alllow us to assign potential $^{13}C$ NMR spectra for the enstatite dissolved with carbon and thus may be useful in exploring the atomic environment of carbon.

• Korean Chemical Engineering Research
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• v.53 no.6
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• pp.808-813
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• 2015

Boron is difficult to be removed from seawater by simple RO (reverse osmosis) membrane process, because the size of boric acid ($B(OH)_3$), the major form of aqueous boron, is as small as the nominal pore size of RO membrane. Thus, the complexation of boric acid with polyols was suggested as an alternative way to increase the size of aqueous boron compounds and the complexation behavior was investigated with Raman spectroscopy. As a reference, the Raman peak for symmetric B-O stretching vibrational mode both in boric acid and borate ion (${B(OH)_4}^-$) was selected. A Raman peak shift ($877cm^{-1}{\rightarrow}730cm^{-1}$) was observed to confirm that boric acid in water is converted to borate ion as the pH increases, which is also correctly predicted by frequency calculation. Meanwhile, the Raman peak of borate ion ($730cm^{-1}$) did not appear as the pH increased when polyols were applied into aqueous solution of boric acid, suggesting that the boric acid forms complexing compounds by combining with polyols.

• Animal Bioscience
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• v.37 no.8
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• pp.1398-1407
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• 2024

Objective: The objective of this study was to determine internal structure spectral profile of by-products from coffee processing that were affected by added-microorganism fermentation duration in relation to truly absorbed feed nutrient supply in ruminant system. Methods: The by-products from coffee processing were fermented using commercial fermentation product, consisting of various microorganisms: for 0 (control), 7, 14, 21, and 28 days. In this study, carbohydrate-related spectral profiles of coffee by-products were correlated with their chemical and nutritional properties (chemical composition, total digestible nutrient, bioenergy values, carbohydrate sub-fractions and predicted degradation and digestion parameters as well as milk value of feed). The vibrational spectra of coffee by-products samples after fermentation for 0 (control), 7, 14, 21, and 28 days were determined using a JASCO FT/IR-4200 spectroscopy coupled with accessory of attenuated total reflectance (ATR). The molecular spectral analyses with univariate approach were conducted with the OMNIC 7.3 software. Results: Molecular spectral analysis parameters in fermented and non-fermented by-products from coffee processing included structural carbohydrate, cellulosic compounds, non-structural carbohydrates, lignin compound, CH-bending, structural carbohydrate peak1, structural carbohydrate peak2, structural carbohydrate peak3, hemicellulosic compound, non-structural carbohydrate peak1, non-structural carbohydrate peak2, non-structural carbohydrate peak3. The study results show that added-microorganism fermentation induced chemical and nutritional changes of coffee by-products including carbohydrate chemical composition profiles, bioenergy value, feed milk value, carbohydrate subfractions, estimated degradable and undegradable fractions in the rumen, and intestinal digested nutrient supply in ruminant system. Conclusion: In conclusion, carbohydrate nutrition value changes by added-microorganism fermentation duration were in an agreement with the change of their spectral profile in the coffee by-products. The studies show that the vibrational ATR-FT/IR spectroscopic technique could be applied as a rapid analytical tool to evaluate fermented by-products and connect with truly digestible carbohydrate supply in ruminant system.

• Korean Journal of Materials Research
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• v.2 no.4
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• pp.279-284
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• 1992

Oxygen adsorption on the single crystal NbC(111) surface was studied by high-resolution electron energy loss and ultraviolet photoelectron spectroscopy. On the NbC(111) surface, oxygen molecules as well as oxygen atoms were adsorbed. Oxygen atoms were located at the 3-fold hollow site of the NbC(111) surface with the frequency of 548c$m^{-1}$. It was found that oxygen molecules had vibrational frequency of 968c$m^{-1}$which was much lower than that of the free oxygen molecule. Also the work function of the NbC(111) surface has increased by adsorption of oxygen molecule. These suggest electron tranfer from the NbC(111) substrate to the 2p${pi}_g$ substrate of the oxygen molecule.

• Journal of the Korean Chemical Society
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• v.47 no.5
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• pp.439-446
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• 2003

Surface-enhanced Raman(SER) spectroscopy was utilized to investigate the adorption orientation of the 4-biphenylcarboxylic acid(BPCA) derivatives, such as 4'-cyano-BPCA(c-BPCA), 4'-mercapto-BPCA(m-BPCA), and 4'-amino-BPCA(a-BPCA), which were adsorbed on Au and Ag colloid monolayers. For the systematic approach, information regarding the adsorption behavior of benzoic acid, biphenyl, and BPCA was applied to the target molecules. From the spectral behaviors of benzene ring, C-H stretching, carboxylate anion, and the other finger printing vibrational modes, it was concluded that only the m-BPCA was adsorbed tilt with thiol group being adsorbed on Au surface, whereas the other molecules were adsorbed flat on both Au and Ag surfaces.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.253.2-253.2
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• 2014

Micro hollow cathode discharges (MHCDs) are high-pressure, non-equilibrium discharges. Those MHCDs are useful to produce an excimer radiation. A major advantage of excimer sources is their high internal efficiency which may reach values up to 40% when operated under optimum conditions. To produce strong excimer radiation, the optimisation of the discharge conditions however needs a detailed knowledge of the properties of the discharge plasma itself. The electron density and temperature influence the excitation as well as plasma chemistry reactions and the gas temperature plays a major role as a significant energy loss process limiting efficiency of excimer radiation. Most of the recent spectroscopic investigations are focusing on the ultraviolet or vacuum ultraviolet range for direct detection of the excimer. In our experiments we have concentrated on investigating the micro hollow cathodes from the near UV to the near infrared (300~850 nm) to measure the basic plasma parameters using standard plasma diagnostic techniques such as stark broadening for electron density and the relative line intensity method for electron temperature. Finally, the neutral gas temperature was measured by means of the vibrational rotational structures of the second positive system of nitrogen.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.587-596
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• 2014

A new ${\pi}$-stacked donor-acceptor (D-A) system, [Ru(1-([2,2'-bipyridine]-6-yl-methyl)-3-(2-cyclohexa-2',5'-diene-1,4-dionyl)-1H-imidazole)(2,2':6',2"-terpyridine)]$[PF_6]_2$ (ImQ_T), has been synthesized and characterized. Similar to its precedent, [Ru(6-(2-cyclohexa-2',5'-diene-1,4-dione)-2,2':6',2"-terpyridine)(2,2':6',2"-terpyridine)]$[PF_6]_2$ (TQ_T), this system has a cofacial alignment of terpyridine (tpy) ligand and quinonyl (Q) group, which facilitates an electron transfer through ${\pi}$-stacked manifold. Despite the presence of lowest-energy charge transfer transition from the Ru-based-HOMO-to-Q-based-LUMO (MQCT) predicted by theoretical calculations by using time-dependent density functional theory (TD-DFT), the experimental steady-state absorption spectrum does not exhibit such a band. The selective excitation to the Ru-based occupied orbitals-to-tpy-based virtual orbital MLCT state was thus possible, from which charge separation (CS) reaction occurred. The photo-induced CS and thermal charge recombination (CR) reactions were probed by using ultrafast visible-pump/mid-IR-probe (TrIR) spectroscopic method. Analysis of decay kinetics of Q and $Q^-$ state CO stretching modes as well as aromatic C=C stretching mode of tpy ligand gave time constants of <1 ps for CS, 1-3 ps for CR, and 10-20 ps for vibrational cooling processes. The electron transfer pathway was revealed to be Ru-tpy-Q rather than Ru-bpy-imidazol-Q.

• Bulletin of the Korean Chemical Society
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• v.32 no.11
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• pp.4011-4015
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• 2011

We explored the interpretation of the well-accepted correlation between the apparent peak maximum position shift and extent of molecular interactions, like hydrogen bonding and dipole-dipole interactions, based on the overlapped multiple band model. The simulation of two overlapped Lorentzian bands was carried out to interpret how the maximum position of a composite peak relates to the relative contributions of two species representing the different levels of molecular interactions, i.e., free (or very weekly bound) vs. strongly bound. To demonstrate the validity of our interpretation of the origin of the peak position shift, the temperaturedependent IR spectra of ethylene glycol were also analyzed. It was found through the analysis of simulated and experimental spectra that the apparent peak shift in certain case can be safely interpreted as the measure of the strength of hydrogen bonding. The result of this study gives a new insight to interpret molecular interactions probed by vibrational spectroscopy.