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Kawaguchi, Kazuhiro; Sanari, Takumi*; Takahiro, Katsumi*; Yamamoto, Shunya; Yoshikawa, Masahito; Nagata, Shinji*
no journal, ,
Silver (Ag) and gold (Au) nanoparticles have strong optical extinction band due to localized surface plasmon resonance (LSPR) in the visible range. These nanoparticles on transparent substrates are being applied to chemical and biological sensors, in which changes in the LSPR features, including resonance wavelength, width and intensity, are observed. In such applications, an intense and sharp absorption band is required for higher detection sensitivity. Our previous work showed that a plasma treatment could be an effective tool to control the LSPR features for Ag nanoparticles prepared by sputter deposition. In the treatment, argon (Ar) plasma cleans up impurities adsorbed on the Ag nanoparticles, resulting in the blue shift and sharpening of the LSPR. In the present work, sputter deposition, and plasma have been employed to fabricate Au nanoparticles with desired optical properties for plasmon-based sensors.
Kawaguchi, Kazuhiro; Sanari, Takumi*; Takahiro, Katsumi*; Yamamoto, Shunya; Yoshikawa, Masahito; Nagata, Shinji*
no journal, ,
Optical extinction spectrum of gold nanoparticles (Au NPs) exhibits a strong peak due to the localized surface plasmon resonance (LSPR). The extinction peak by LSPR change in dependence on a medium surrounding Au NPs. Recently, new sensing materials have been developed for organic gas sensors using LSPR. The extinction peak by LSPR, however, often differs from the ideal values because of impurities adhered on Au NPs surface in air. In this study, plasma and ion sputtering treatments have been employed to eliminate impurities on the Au NPs surfaces. As the result, it was found that carbonaceous impurities decrease significantly from X-ray photoelectron spectroscopy and the wavelength of the LSPR extinction peak close to ideal value. In addition, the observation by scanning electron microscopy was indicated no significant change in the morphology of Au NPs after the treatments. We concluded plasma and ion sputtering treatments were effective methods to obtain Au NPs with clean surfaces.