Accumulation and interparticle connections of triangular Ag-coated Au nanoprisms by oil-coating method for surface-enhanced Raman scattering applications

作者：Noda Yuta; Asaka Toru; Fudouzi Hiroshi; Hayakawa Tomokatsu^*

来源：Applied Surface Science, 2018, 435: 687-698.

DOI：10.1016/j.apsusc.2017.11.176

• Au nanoprisms
• Localized surface plasmon resonance (LSPR)
• Surface-enhanced Raman scattering (SERS)
• Oil-coating method
• Ag coating

To examine the optical responses of surface-enhanced Raman scattering (SERS) for tuned plasmonic nanoparticles, triangular Ag-coated Au (Au@Ag) nanoprisms with different sizes were separately synthesized, which were well controlled in their size (edge-length) and localized surface plasmon resonance (LSPR) wavelength (69.0 +/- 8.4 to 173.8 +/- 25.6 nm in size and 662-943 nm in LSPR wavelength). The mechanism of Ag shell formation on the Au nanoprisms was also studied with scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDS). The Au@Ag nanoprisms were immobilized by covering a colloidal solution containing the nanoprisms with silicone oil and evaporating the solvent in the oil (oil-coating method) so as to form a layer of accumulated plasmonic Au@Ag nanoprisms that had LSPR peak wavelengths tuned from 839 to 1182 nm. The accumulation conditions were analyzed by field-emission scanning electron microscopy (FE-SEM) and a Raman mapping technique. The Au@Ag nanoprisms under excitation at 632.8 nm exhibited higher SERS signals of rhodamine 6G, and SERS-mapped images of the novel immobilized films were obtained at different magnifications. It was concluded that accumulated Au@Ag nanoprisms undergoing tip-planar interconnections could produce enhanced local fields, resulting in higher SERS signals.

• 出版日期2018-3-30