Coating silver tree‐like fractal structure with silica layer for inhibiting chemical reactions of analytes in surface‐enhanced Raman scattering
Hiroya Watanabe, Yurin Hishii, Kanna Kishimoto, Kohei Nogami, Qingyuan Ma, Tomoya Niki, Tomoki Kotani, Toshihiko Kiwa, Satoru Shoji, Takahiro Ohkubo, Jun Kano, Nobuyuki Takeyasu- Materials Chemistry
- Electrical and Electronic Engineering
- Surfaces, Coatings and Films
- Surfaces and Interfaces
- Condensed Matter Physics
- Electronic, Optical and Magnetic Materials
Silica coating is performed onto silver tree‐like fractal structures, which are self‐grown in a solution, through a wet process using tetraethyl orthosilicate. Surface‐enhanced Raman scattering (SERS) of para‐aminothiophenol (p‐ATP) is measured on the silver tree‐like fractal structures with/without silica layer at the excitation wavelength of 532 nm. p‐ATP is chemically transformed into dimercaptoazobenzene (DMAB) on the non‐coated silver tree‐like fractal structures, where DMAB peaks are clearly observed, during the SERS measurements. The DMAB peaks decrease/disappear on the silica‐coated ones although the p‐ATP peaks were observed. The results indicate that the chemical transformation is inhibited on the silica‐coated ones. The sensitivity is decreased by half compared to the non‐coated silver tree‐like fractal structures, where the lower detection limit is estimated to be ∽2×10‐5 mol/L for p‐ATP. The silica coating is advantageous for inhibiting chemical transformations of analytes, enabling identification/estimation of chemicals in unknown sample with SERS similarly to conventional Raman spectroscopy.
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