Detecting very small quantity of molecular probes in solution using nano-mechanically made Au-cavities array with SERS-active effect |
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Authors: | Chia-Wei ChangAuthor VitaeJiunn-Der LiaoAuthor Vitae Yin-Yi LinAuthor VitaeChih-Chiang WengAuthor Vitae |
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Affiliation: | Department of Materials Science and Engineering, National Cheng Kung University, No. 1, University Road, Tainan 70101, Taiwan |
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Abstract: | Well-ordered nano-mechanically made Au-cavities array (nAu) is tailored as a functional surface with high density tip-to-tip cavities, adjustable indentation depths, and a number of edges within the nanostructures. In this study, the nAu was fabricated by a physical way and utilized as a characterization tool with the advantage of preventing samples from chemical or residual contaminations. Two types of molecular probe solutions: 5,5′-dithio-bis-(2-nitrobenzoic acid) (DTNB) and Rhodamine 6G (R6G) were evaluated. For DTNB solution, the chemically adsorbed monolayer was formed upon the nAu, which resulted in the effect of surface enhanced Raman scattering (SERS), mainly induced by the combined chemical and electromagnetic effects. Within the range of 1 × 10−23 to 3.2 × 10−22 mole, Raman intensity and the quantity of DTNB molecules exhibited a sharp exponential relationship. For R6G solution within the equivalent nAu and the identical range, the relationship exhibited nearly linear; however, within an extended range of 1 × 10−23 to 3.2 × 10−21 mole, a moderate exponential relationship was obtained. The enhancement factors for detecting DTNB and R6G solutions using the nAu could be optimized to 1.62 × 108 and 4.60 × 107, respectively. |
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Keywords: | Gold (Au) Nanostructures Characterization tool Monolayer |
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