- 著者
- Song Wenbo Okamura Masayuki Kondo Toshihiro Uosaki Kohei
- 出版者
- Elsevier
- 雑誌
- Journal of Electroanalytical Chemistry (ISSN:00220728)
- 巻号頁・発行日
- vol.612, no.1, pp.105-111, 2008-01-01
- 被引用文献数
- 9
Amounts of gold nanoclusters (GNCs) in multilayer assembly with polymer binding layers has been demonstrated to be controlled by pH and ionic strength of the polymer solution when GNCs covered with mercaptoundecanoic acid (MUA) were assembled on a solid substrate in a layer-by-layer (LBL) fashion utilizing terminal carboxylate groups as charged sites to electrostatically bind to protonated amine groups of poly(allylamine hydrochloride) (PAH), which was used as a binding layer. Formation of these GNC multilayers was followed by monitoring the electrochemical response of the ferrocene moiety attached to the GNC core, which acted as a redox probe. The apparent acid dissociation constant of MUA on the GNC surface estimated from correlation between the amount of adsorbed GNCs and pH of the PAH solutions was in good agreement with those previously reported. Facile charge transport within LBL multilayer assemblies formed under various pH and/or ionic strengths of polymer solution revealed an open porous film microstructure contributing to facile charge transfer by hopping through GNC sites as well as with the aid of electrolyte in pores in such architectures. This study provides significant fundamental basis for construction of highly charged complex structures containing redox groups and useful applications in catalysis and devices fabrication based on charge transfer.
- 著者
- Kim Young-ho Zhao Jianwei Uosaki Kohei
- 出版者
- American Institute of Physics
- 雑誌
- Journal of Applied Physics (ISSN:00218979)
- 巻号頁・発行日
- vol.94, no.12, pp.7733-7738, 2003-12-15
- 被引用文献数
- 8
Nanosized patterns of tantalum oxide were fabricated on a tantalum substrate by applying a potential pulse utilizing current sensing atomic force microscopy (CSAFM). The dimensions of the dots were strongly dependent on the bias applied, scan rate, and potential pulse duration. By controlling these variables, the minimum size nanodots with full width at half maximum of 35 nm was achieved. Immediately after pattern formation, the electrical properties of the Ta oxide nanodots were measured using CSAFM. The charge transport at the CSAFM tip and the nanosized Ta oxide dot can be described by Poole–Frenkel type conduction. The relative dielectric constant of the nanosized Ta2O5 dots was calculated to be 17.8–24.3, showing that the quality of the oxide was high. In addition, by controlling the substrate bias applied, pulse duration, and tip scan speed, nanosized Ta oxide lines with the desired dimensions were prepared.