Youngwook Choi

Hanyang University, Sŏul, Seoul, South Korea

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Publications (2)1.46 Total impact

  • Seungkwang Roh · Jiyoung Jang · Jihoon Oh · Youngwook Choi · Whikun Yi
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    ABSTRACT: Defect-free single-walled nanotubes (SWNTs) were prepared by chemical reaction from normal SWNTs, and field emission and dispersion properties of both were compared. The field emission currents of defect-removed SWNTs are measured as a function of the number of defects, i.e., reaction time with methyl acrylate. As the defects are removed from surface of nanotubes, the SWNTs become entangled and more separated between themselves, thus the separated SWNTs have the higher aspect-ratio than the pristine SWNTs. Consequently the SWNTs having the small number of defects show the higher field emission currents. It was also shown in the UV absorption spectra of the samples in ethanol in the field emission experiment, that the more defect-removed SWNTs are better dispersed in the solvent.
    No preview · Conference Paper · Aug 2004
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    ABSTRACT: Adsorption behaviors of alkanethiol molecules are investigated on the surface of single-walled carbon nanotubes with vibrational spectrophotometer. Butanethiol ( C <sub>4</sub> H <sub>9</sub> SH ), hexanethiol ( C <sub>6</sub> H <sub>13</sub> SH ), nonanethiol ( C <sub>9</sub> H <sub>20</sub> SH ), and dodecanethiol ( C <sub>12</sub> H <sub>25</sub> SH ) molecules are adsorbed on the nanotube surface, and infrared spectra are measured as a function of concentration of the adsorbed molecules and molecular chain length. Alkanethiol molecules are thought to be strongly adsorbed on the SWNT surface. The active adsorption sites in the nanotube surface are thought to be Stone–Wales defects (5–7 ring defects). © 2004 American Vacuum Society.
    Full-text · Article · Jun 2004 · Journal of vacuum science & technology. B, Microelectronics and nanometer structures: processing, measurement, and phenomena: an official journal of the American Vacuum Society