• 제목/요약/키워드: Surface chemistry

검색결과 3,823건 처리시간 0.039초

Raman Spectroscopic Study of Benzonitrile on Silver Surface

  • Boo, Doo-Wan;Kim, Kwan;Kim, Myung-Soo
    • Bulletin of the Korean Chemical Society
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    • 제8권4호
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    • pp.251-254
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    • 1987
  • The surface-enhanced Raman scattering(SERS) of benzonitrile in a silver sol was investigated. It was concluded that the molecule adsorbed onto the silver surface via the nitrogen lone pair electrons. Using the surface selection rule, the orientation of the benzene ring with respect to the surface plane could not be determined conclusively. However, it seemed likely that benzonitrile is adsorbed edge-on to the surface. It was demonstrated that the SERS technique provides a useful method for detailed characterization of the chemisorbed layer.

Textural properties of Activated Carbons from Wild Cherry Stones as Determined by Nitrogen and Carbon Dioxide Adsorption

  • Alaya, M.N.;Youssef, A.M.;Karman, M.;Abd El-Aal, H.E
    • Carbon letters
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    • 제7권1호
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    • pp.9-18
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    • 2006
  • Activated carbons were obtained by activating wild cherry stones with different concentrations of phosphoric acid or zinc chloride at different temperatures. The adsorption of $N_2$ at 77 K and of $CO_2$ at 273 K was followed and the data were analyzes by considering different adsorption models. The activated carbons obtained measured high surface area with the most of the surface in all samples located in micropores. Fair agreement was found between the nitrogen surface areas calculated from the BET-, t-, ${\alpha}$- and DR- methods, although the first three are based on surface coverage whereas the latter is based on micropore filling. The carbon dioxide surface areas calculated by the DA equation were smaller than the comparable nitrogen areas. This was ascribed to domination of surface coverage mechanism, the absence of activated diffusion process. Based on this explanation the $CO_2$-surface areas as calculated by DA equation should be taken with great reservation.

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Study on sputtering yield of tungsten with different particle sizes: Surface roughness dependence

  • Kwon, Tae Hyun;Park, Sangjune;Ha, Jeong Min;Youn, Young-Sang
    • Nuclear Engineering and Technology
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    • 제53권6호
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    • pp.1939-1941
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    • 2021
  • The sputtering yield of tungsten pellets composed of different particle sizes of <1, 12, 44-74, and 149-297 ㎛ was systematically investigated by bombardment with Ar+ ions accelerated at 2.0 keV in an ultra-high vacuum chamber. We found that the tungsten sample fabricated from larger particles had a higher surface roughness, based on the surface profile results. Using the data of the surface roughness for the four types of tungsten pellets, we confirmed that the sputtering yield for a tungsten pellet with the highest surface roughness was 7 times lower than that of the lowest surface roughness. This could be due to the redeposition of sputtered tungsten particles onto neighboring asperities.

Surface Enhanced Raman Scattering of Methoxybenzonitriles in Silver Sol

  • Boo, Doo-Wan;Kim, Myung-Soo;Kim, Kwan
    • Bulletin of the Korean Chemical Society
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    • 제9권5호
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    • pp.311-317
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    • 1988
  • The surface-enhanced Raman scattering(SERS) of methoxybenzonitrile in a silver sol was investigated. All of ortho-, meta-, and para-substituted benzonitriles were found to adsorb on the silver surface via the nitrogen lone pair electrons. The benzene ring of meta derivative seemed likely to stand perpendicular to the silver surface, while the benzene rings of both otho and para derivatives assumed tilted stances with respect to the surface. The SERS technique appeared to be a useful means to study the substituent electronic effects.

Effect of Different Pretreatments on Indium-Tin Oxide Electrodes

  • Choi, Moonjeong;Jo, Kyungmin;Yang, Haesik
    • Bulletin of the Korean Chemical Society
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    • 제34권2호
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    • pp.421-425
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    • 2013
  • The effect of pretreatment on indium-tin oxide (ITO) electrodes has been rarely studied, although that on metal and carbon electrodes has been enormously done. The electrochemical and surface properties of ITO electrodes are investigated after 6 different pretreatments. The electrochemical behaviors for oxygen reduction, $Ru(NH_3){_6}^{3+}$ reduction, $Fe(CN){_6}^{3-}$ reduction, and p-hydroquinone oxidation are compared, and the surface roughness, hydrophilicity, and surface chemical composition are also compared. Oxygen reduction, $Fe(CN){_6}^{3-}$ reduction, and p-hydroquinone oxidation are highly affected by the type of the pretreatment, whereas $Ru(NH_3){_6}^{3+}$ reduction is almost independent of it. Interestingly, oxygen reduction is significantly suppressed by the treatment in an HCl solution. The changes in surface roughness and composition are not high after each pretreatment, but the change in contact angle is substantial in some pretreatments.

Photocatalytic activity of various $TiO_2$ nanostructures

  • Kim, Myoung-Joo;Kim, Kwang-Dae;Tai, Wei-Sheng;Seo, Hyun-Ook;Luo, Yuan;Kim, Young-Dok
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2009년도 제38회 동계학술대회 초록집
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    • pp.34-34
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    • 2010
  • Activities of various $TiO_2$ nanostructures in photocatalytic decomposition of methylene blue and toluene were determined in order to shed light on the relationship between structures and photocatalytic activity. Commercially available P-25 samples were used in the present work. In addition, $TiO_2$ nanostructures were synthesized using atomic layer deposition (ALD). We show that change in the surface structure of $TiO_2$ upon variois surface treatments results in variation in photocatalytic activity. In particular, increase in the number of OH groups on the surface leads to the enhancement in photocatalytc activity. Surface OH groups increases adsorption reactivity of organic reactants, thereby increasing activity in photocatalytic decomposition of methylene blue and toluene.

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