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Detection of Ions and Radicals Using Single Walled Carbon Nanotubes
Sehun Jung,Seunghyun Baik,Jaeboong Choi,Jongchul Lee,Seunghyun Hong,Youngjin Kim 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.I
Single-walled carbon-nanotube (SWNT) sensors, fabricated by using alternative current dielectrophoresis, were used to detect decomposed ions and radicals in plasma. In this work, we monitored the electrical conductance of the SWNT sensors in argon (Ar) and sulfur hexafluoride (SF$_6$) plasma. Ar and SF$_6$ were decomposed in plasma status. The electrical conductance of the SWNT arrays in Ar plasma increased due to an electronic interaction between SWNT and oxidative decomposed ions. In contrast, the nanotube arrays in SF$_6$ plasma exhibited a drastic decrease in conductance due to the fluorination of the SWNT by decomposed radicals, rather than charge transfer by decomposed ions. These results demonstrate that electronic detection of the decomposed ions and radicals is possible with SWNT sensors.
Neutralized fluorine radical detection using single-walled carbon nanotube network
Jung, Sehun,Hong, Seunghyun,Park, Byoungjae,Choi, Jaeboong,Kim, Youngjin,Yeom, Geunyoung,Baik, Seunghyun Elsevier 2008 Carbon Vol.46 No.1
<P><B>Abstract</B></P><P>It is known that single-walled carbon nanotubes (SWCNTs) can be functionalized by fluorine gas. Here, we report neutralized fluorine radical detection using a matted sheet of SWCNTs, prepared by alternating current dielectrophoresis. Upon exposure to neutralized radicals containing fluorine atoms in a plasma, as model analytes, the conductance of the SWCNT matt showed fast modulation. The transduction mechanism was investigated by electrical transport measurements, X-ray photoelectron spectroscopy and Raman spectroscopy. Metallic nanotubes were shown to react covalently to the near exclusion of semiconducting species. The selectivity was promoted by the curvature-induced strain of the nanotubes. The results open new opportunities for the detection of fluorine radicals at specific locations inside the reaction zone using a simple, miniaturized carbon nanotube network.</P>
Jung, Soon Jung,Kim, Do Hwan,Lee, Jun Young,Kim, Sehun,Hong, Suklyun American Chemical Society 2012 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.116 No.12
<P>The adsorption of purine on Ge(100) has been investigated using scanning tunneling microscopy (STM) supported by ab initio theoretical calculations. Purine molecules were found to spontaneously adsorb via double dative bonding with both ring nitrogen atoms (N(1) and N(7)) donating charge to the two neighboring Ge down atoms across the dimer row trench at room temperature. The additional surface Ge atom reacts with C(8) or N(9) to stabilize the positive charge of the datively bonded N(7) atom. The reaction with N(9) atom induces N(9)H bond dissociation. This reaction mechanism is different from the “isotope exchange reaction” observed in solution chemistry, which results in α-CH dissociation. Under vacuum conditions, the CH dissociation is unfavorable without a stabilizing agent to stabilize the zwitterions. In the absence of water, we find the surface Ge atom contributes to stabilization by donating an electron of its dangling bond. The electron donated from the surface Ge atom is transferred into the resonance structure of the purine and stabilizes the system.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2012/jpccck.2012.116.issue-12/jp211099z/production/images/medium/jp-2011-11099z_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp211099z'>ACS Electronic Supporting Info</A></P>
Single-walled carbon nanotube sensors for monitoring partial discharge induced dissociation of SF6.
Jung, Sehun,Choi, Jaeboong,Kim, Youngjin,Lee, Jongchul,Chang, Yongmoo,Baik, Seunghyun American Scientific Publishers 2009 Journal of Nanoscience and Nanotechnology Vol.9 No.12
<P>We proposed to use a miniature single-walled carbon nanotube (SWNT) sensor, fabricated by alternating current dielectrophoresis, to detect dissociated and oxidized sulfur hexafluoride (SF6) gas species generated by partial discharge (PD) activity in a concealed chamber such as gas-insulated switchgear (GIS). The SWNT sensor did not react with pure SF6 gas but sensitively responded to the dissociated and oxidized SF6 species. Also, the SWNT sensor could be regenerated by purging with fresh air since the transduction was based on the physisorption of analytes. Therefore, the SWNT sensor is a promising device for the detection of the dissociated and oxidized SF6 species and for the monitoring of the PD activity inside GIS.</P>