Synthesis And SERS Activity Of Indium-silver Bimetallic Nanocomposites

Surface-enhanced Raman scattering(SERS) spectroscopy has a broad application in the biological medicine, science, chemistry and other fields for its high sensitivity, high selectivity, small fluorescence interference and strong analysis ability. It can be implemented on various probe spectrum detection and analysis of different molecules. The performance of SERS substrate has a decisive role the application of SERS spectra. Bimetallic nanocomposites substrate is able to combine the excellent properties of two kinds of metal to improve the performance of SERS substrate. However, the SERS enhancement mechanism has not yet fully understood, expanding different kinds of SERS substrate materials will provide certain reference for SERS enhancement mechanism research. This paper mainly focuses on developing a new SERS substrate. We have experimentally synthesized the In-Ag bimetallic nanocomposites SERS substrate. And we have studied the SERS activity of In-Ag bimetallic nanocomposites with comparison with the Ag nanoparticles SERS substrate, the main contents are as follows,In the first chapter we have given a brief introduction to the bimetallic nanocomposites materials and SERS spectroscopy which including the methods of design and preparation of bimetallic nanocomposites materials, application of bimetallic nanocomposites materials, enhancement mechanism, the methods of design and preparation of SERS substrate, and application of SERS substrate.The second chapter introduces all kinds of instruments and test principle which are used in our research.In the third chapter we put forward a simple method to prepare In-Ag bimetallic nanoparticles and the morphology and the absorption spectrum are shown. We also study the SERS activity of In-Ag bimetallic nanocomposites substrate comparing with Ag nanoparticles SERS substrate, the results indicate that:1. The absorption peaks of In-Ag bimetallic nanocomposites spectra close to the incident Raman laser wavelength is higher than that of Ag nanoparticles absorption spectra.2. Our prepared In-Ag bimetallic SERS substrate shows very high enhancement factor which is up to3.819×109(R6G 611cm-1), the enhancement factor is nearly two times larger than that of Ag nanoparticles with the similar particle size, the probe molecule detection limit for In-Ag bimetallic nanocomposites SERS substrate is at least 10-10 M(CV, R6G).3. The enhancement effect of In- Ag bimetallic nanocomposites SERS substrate better than that of the Ag nanoparticles SERS substrate mainly attributed to inter-particle effects between In and Ag nanoparticles. It enhanced the local surface plasmon resonance and cause electromagnetic field enhancement around the probed molecules.