• Bulletin of the Korean Chemical Society
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• v.23 no.11
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• pp.1604-1610
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• 2002

In the present work, we studied thiram on silver surface by SERS. Investigations of disulfides with SERS revealed that the molecules undergo a surface reaction on silver, namely easy cleavage of the S-S bond. We believe that the two S atoms of resonance formed from the thiram may be chemisorbed strongly on Ag sol. This resonance form adheres perpendicularly to the Ag surface via the two S atoms, since the ${\delta}(CH3)$ and n (CN) mode perpendicular to the surface showed strong enhancement. The important roles of halide anion adsorption have been discussed and the pH effects of thiram on Ag sol in acidic, neutral, and alkaline conditions were examined.

• Journal of Microbiology and Biotechnology
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• v.14 no.6
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• pp.1157-1162
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• 2004

A well-holder type piezoelectric chloramphenicol (CAP) immunosensor which was prepared by binding an anti­CAP antibody to the chemisorbed monolayers of various thiol or sulfide compounds over the gold electrode surface of quartz crystals through a carboxyl-amine coupling procedure, using the activation with l-ethyl- 3-(3-dimethylarninopropyl)carbodiimide­HCl and N-hydroxysulfosuccinimide, was determined for its responses to CAP, CAP succinate, and water-soluble CAP. The reaction phase used in the well holder was 0.01 M phosphate buffer (pH 7.4), and the solvent for analyte dissolution varied according to the solubility of the individual analyte. The analyte detection which was indicated by a steady-state frequency shift was finished within 10 min, except for CAP dissolved in methanol. The responses of CAP succinate and water-soluble CAP in the reaction phase were very stable, while a minute fluctuation was found with CAP.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1988.11a
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• pp.35-48
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• 1988

상대 접촉하고 있는 물체에 미끄럼 운동이 가해질 경우 마찰에 의해 발생되는 거의 모든 에너지는 열로써 나타나게 된다. 이러한 마찰열은 주로 adhered junctions의 파괴 및 표면돌기(surface asperities)들의 소성 변형에 의한 열역할적 비가역 반응의 결과로 발생된다. 접촉부위의 발생열은 양 접촉제의 접촉면에 전달되어 접촉표면 온도의 급격한 증가를 초래하며 그 결과로 여러가지 surface phenomena, 즉 마찰, 마모, 산화(oxidation), 부식 및 구조적 열화(structural degradation) 금속학적 상변화등에 큰 영향을 미치게 된다. 딸서 볼 및 로울링 엘레먼트 베어링, 기어, 캠과 태핏, 브레이크 등 기계요소의 설계를 위한 주인자로서 근래에 들어 접촉표면의 온도가 주목받고 있다. 표면에 존재하는 layer로서는 금속표면에 응착시킨 coating layers, contaminant films, physisorbed 또는 chemisorbed films, oxide layers 또는 마찰열에 의해 형성되는 경도가 아주 높은 내마모층(hard wear-resistant layers) 등이 고려될수 있다. 낮은 열전도성을 가진 oxide film이 접촉 표면이 온도를 증가시킨다는 것이 Jaeger에 의해 지적되었으며 Ling과 Lai는 moving heat sjource가 가해지는 layered surface의 표면온도분포를 구하면서 substrate와 thermal property가 다른 layer가 존재하게 되면 그 두께가 아주 얇더라도 (1 마이크론 정도) 표면온도는 크게 변화됨을 보였다.

• Proceedings of the Korean Vacuum Society Conference
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• 1992.02a
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• pp.3-10
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• 1992

pphotostimulated desorpption of NO chemisorbed on ppt(001) at 80K has been studied by the (1+1)-resonance-enhanced multipphoton ionization((1+1)-REMppI) technique. A linearly ppolarized ArF excimer laser ( =193 nm, 6.41eV) is used as the ppumpp laser. A high adsorpption rate selectivity was found in the expposure deppendence of the NO desorpption yield. The NO desorpption yield increases drastically when the amount of NO expposure exceeds ~1.8 L. This result shows that the amount of NO sppecies with a large cross section for pphotostimulated desorpption increases drastically at higher NO coverages. Using scanning tunneling microscoppy, we have observed structural modifications of the chlorinated Si(111)-7$\times$7 surface induced by 266nm laser irradiation. At very low laser fluence of 0.7mJ/$\textrm{cm}^2$, at which thermal desorpption can be ignored, a pperiodic stripped ppattern of a single domain is imaged. This ppattern consists of flat terraces and narrow grooves of ~60 and ~10A in width, resppectively.

• Journal of the Korean Ceramic Society
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• v.36 no.7
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• pp.705-710
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• 1999

Stability and chemical durability for aqueous casting of BaTiO3 slurry with polycarylic acid(PAA) were studied. PAA was well chemisorbed on surface of BaTiO3 powder at neutral pH but did not chemically adsorbed at low pH. The amount of Ba dissolution in aqueous BaTiO3 slurry was abruptly increased at strong acid pH2 and also at high amount of PAA. Protection of Ba dissolution and stability of slurry could be obtained through the optimization of slurry conditions such as pH amount of surfactant and solid content.

• Bulletin of the Korean Chemical Society
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• v.27 no.12
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• pp.2037-2039
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• 2006

The adsorption and surface reactions of $SO_2$ on Ni(100), c($2{\times}2$)_O/Ni (100) and NiO(111)/Ni(100) surfaces have been investigated using X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) technique. On Ni(100), chemisorbed $SO_2$ is formed at 160 K. When $SO_2$ is adsorbed on c($2{\times}2$)_O/Ni(100) at 160 K, $SO_2$ reacts with oxygen to form $SO_3$ and trace amount of $SO_4$ species. $SO_3$ is adsorbed on this surface with its $C_3$ axis perpendicular to the surface. On a NiO(111)/Ni(100) surface, both $SO_3$ and $SO_4$ species are formed at 160 K from adsorbed $SO_2$.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.372-372
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• 2010

We have investigated adsorption of selenophene on Si(100) at room temperature using high resolution photoemission spectroscopy (HRPES) and near edge X-ray absorption fine structure (NEXAFS) in the partial electron yield (PEY) mode. The Si 2p, C 1s, Se 3d spectra of selenophene on Si(100) show that selenophene is nondissociatively chemisorbed on Si(100)-$2{\times}1$ through [2+2] cycloaddition. NEXAFS has been conducted to characterize the adsorption geometry of selenophene on Si(100). Since the $\pi^*$ orbital of C=C bond show good angular dependence in carbon K-edge NEXAFS spectra, the angle $53{\pm}5^{\circ}$ determined from NEXAFS spectra. This majority structure is consistent with the [2+2] cycloaddition of selenophene to the dimer of the Si(100)-$2{\times}1$ surface.

• Journal of the Korean institute of surface engineering
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• v.32 no.3
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• pp.276-280
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• 1999

Electrical properties of electrochromic (EC) InN thin films prepared by rf ion plating were studied. There was a correlation between the electrical properties and the electrochromism in the InN films, particularly, carrier concentration changes were responsible for the electrical resistivity changes of the films due to the electrochromism. These carrier concentration changes were caused by chemisorbed hydroxyl groups and protons. From these results, it was proved that the carrier concentration changes of the InN films was responsible for the electrochromism in the visible and near-infrared region.

• Bulletin of the Korean Chemical Society
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• v.9 no.6
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• pp.388-393
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• 1988

The chemisorption of CO molecules on polycrystalline nickel surface has been studied by investigating the resulting chemisorbed species with the X-ray photoelectron spectroscopy at temperatures between 300K through 433K. It is found that the adsorbed CO molecules are dissociated by the simple C-O bond cleavage as well as by the disproportionation reaction at temperatures above 373K. The former type dissociation is more favored at low coverages and at elevated temperatures. The isotherms of CO chemisorption are obtained from the xps intensities of C 1s peaks, and then the activation energy of the dissociative adsorption is estimated as a function of the CO exposure. These activation energies are extrapolated to zero coverage to obtain the activation energy of chemisorption in which thermal C-O bond cleavage takes place. The value obtained is 38.1 kJ/mol.

• Bulletin of the Korean Chemical Society
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• v.12 no.5
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• pp.574-582
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• 1991

The CO molecules adsorbed on Ni(111) surface is studied in the cluster approximation employing EH method with self-consistent charge iteration. The effect of CO coverage is simulated by allowing the variation of valence state ionization potentials of each Ni atom in model cluster according to the self-consistent charge iteration method. The CO coverage dependent C-O stretching frequency shift, adsorption site conversion, and metal work function change are attributed to the charge transfer between metal surface and adsorbate. For CO/Ni(111) system, net charge transfer from Ni surface to chemisorbed CO molecules makes surface Ni atoms be more positive with increasing coverage, and lowers Ni surface valence band. This leads to a weaker interaction between metal surface valence band and Co $2{\pi}^{\ast}$ MO, less charge transfer to a single CO molecule, and the bule shift of C-O stretching frequency. Further increase of coverage induces the conversion of 3-fold site CO to lower coordination site CO as well as the blue shift of C-O stretching frequency. This whole process is accompanied by the continuous increase of metal work function.