| Surface-enhanced Raman spectroscopy(SERS) is a vibrational spectroscopy technique with high sensitivity in surface detection. After years of development, SERS has become an important tool in the detection field of surface analysis since it has been found in 1970 s. SERS can give a wealth of information about the structure of matter, it is to be compared with fluorescence spectroscopic detection in molecular detection due to its high detection sensitivity. So it is widely used in physics, biology and chemistry. SERS intensity is influenced by many factors. For example, the nature of the metal, size, morphology, particle spacing,etc. Only a very few metals(gold, silver, copper, etc.) having a SERS effect.Silver nanoparticles are widely used in SERS substrate material because of its simple preparation method, low production cost, high SERS activity,etc. For a long time, since the universality of substrate material and the substrate surface morphology is poor, which greatly limits the practical application of the SERS effect on the types of materials and systems and a variety of atomically smooth surface. Therefore, how to prepare high sensitivity, stability and repeatability as well as a large number of "hot spots" controlled SERS substrate remains an important challenge.In this paper, the preparation and SERS properties of three different types of silver particles were studied. The spherical silver, flower-like silver, thorn-like silver is prepared. The influence of different parameters on the preparation of silver and the growth mechanism of silver were investigated. SERS performance of different types of silver particles were analyzed in order to study the effect of particle size, spacing, morphology and other factors on the SERS, and good substrates were prepared for the actual SERS test.The main contents and conclusions are as follows:(1) At 130° C oil bath environment, we prepared an average particle diameter of 80 nm spherical silver by sodium citrate reduction of silver nitrate in the presence of PVP. After addition of PVP, reducing the number of wire, rod silver. We also prepared three kinds of SERS substrate in three different assembly ways. They were MF substrate, D substrate, M substrate respectively. Using rhodamine 6G(R6G) as a probe molecule, compare the performance of three SERS substrate. It was found that the MF exhibited a high sensitivity(The detection limit of R6 G was 10-9 mol/L) and reproducibility. The enhanced reason was analyzed by finite difference time domain(FDTD) method. The results showed that the experimental results are consistent with the theoretical simulation.(2) Three flower-like sliver particles with different morphologies and same size were prepared by ascorbic acid reducing silver nitrate in the presence of PVP. The diameter of flower-like silver was 300 nm. Using R6 G as a probe molecule, compare the SERS performance of three flower-like silver. The results show that the silver particles of moderate roughness have the best SERS performance.(3) Different types of thorn-like silver were prepared. The growth mechanism of the particles being studied by adjusting the concentration of silver nitrate, silver nitrate concentration and amount of formaldehyde, the amount of formaldehyde to influence the morphology of the particles. Using R6 G as a probe molecule, we compared the SERS performance of different types of thorn-like silver. The results show that the thorn-like silver particles with long thorn rod have the worst SERS performance, while the particles with short rod was best.(4) Three SERS substrates were prepared by spherical silver, flower-like silver, thorn-like silver respectively. Using R6 G as a probe molecule, we compared the SERS performance of three substrates. The results show that spherical silver and flower- like silver have a strong SERS activity. Malachite green solution was detected on flower-like SERS substrate. The detection limit was 0.01 mg / L. |
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