Fabrication And Application Of Several Surface Enhanced Raman Scattering Substrate

Surface-enhanced Raman scattering （SERS） technology has high sensitivity,compared with normal Raman method, is an attractive phenomenon that hugelyincreases Raman signals with cross sections of up to2-14orders of magnitude. SERScan be detected on the surface of the metal adsorption in the single molecule layermolecules, and provide the molecular structure of the rich information. Therefore, as apotential development of spectral analysis technology, SERS has applied in thechemical, physical, biological, medical, environmental monitoring, public security andother aspects. As we know, it is still a challenge to fabricate a SERS substrate of highsensitivity, stability and reproducibility for quantitative detection of target molecules. Soit is great significance for research SERS substrate. In this paper, three substrates ofdendrite, nanoparticl and nanomaterial array have been studied for SERS.The main research works are listed as following:First, noble metals dendrites applied in surface-enhanced Raman research. Wereported a simple method for large-scale synthesis of Ag dendrites with [100],[110],and [111] growth directions by the hydrothermally assisted galvanic displacement.Three kinds of Ag dendrites can be obtained by adjusting the amount of polyvinylpyrrolidone. Ag dendrites were employed to study the SERS effect by using R6G as aprobe molecule. The results showed that （1） there is a corresponding relation betweenthe false color plot of Raman intensity and the dendrite morphology;（2） the best SERSeffect was obtained on the primary axis of every dendrites;（3） the Ag dendrites with[100] growth direction have the best SERS enhancement and [110] growth direction theworst;（4） the [100] dendrite growth is not sensitive to the varying of z value in theSERS detection. Next we use the same method to synthesis gold dendrites and researchits surface-enhanced Raman scattering effect. The results showed that it still haveRaman effect when the concentration is low to10^-8M.Second, Surface-enhanced Raman scattering effect was demonstrated on nanomaterial array, which was fabricated by Au deposition on the profile of etched Sinanowires. This structure was easy for optical focusing and raised the utilization of thesubstrate in the SERS detection. The results showed that at the Au thickness of8nm,the profile arrays enhancement effect reached the maximal,6.2times of the plane arraysenhancement. Ultrasensitive SERS signal from the profile array structures wereobserved, even though the concentration of the R6G was as low as1×10^-11M with theenhancement factor of2.3×10⁹.Third, Large-scale and uniform porous magnetite nanoparticles with averagediameter of60nm were successfully prepared using a facile hydrothermal approach.SERS substrate was fabricated by depositing Au film on the surface of nanoparticles.The results showed that the Raman intensity gradually increase as the Au thicknessincreases from4to10nm, and Raman intensity change little as the thickness increasesfrom10to20nm. Furthermore, these nanoparticles were self-assembled by usingexternal magnetic field and employed to modify glassy carbon electrode, whichdisplayed excellent electrochemical sensitivity in detecting dopamine and couldselectively distinguish dopamine in the presence of ascorbic acid.