Synthesis, Characterization, And Application Of SERS-active Substrates

Surface-enhanced Raman scattering (SERS) has been widely applied in surface science, analysis science and biological system due to its sensitive, rapid and sensitive sensing capability. However, the application of the present SERS technique is mainly depended on the nature of the SERS-substrates. Thus, the search for SERS-active substrates with uniformity, high stability and strong enhancement is still a research focus in SERS field.This dissertation is divided into four parts. The first chapter is an overview on the recent research of the SERS, including follow:1) discovery and mechanism of SERS. 2) SERS substrates material.3) Synthesis of SERS substrates.4) Application of SERS. 5) Purpose and content of the dissertation.In chapter 2, we proposed a novel method to prepare a dense monolayer of nanosilver SERS-active substrates. The AgNPs was formed on the surface via the bilayer of CTAB. During the airing, a monolayer of AgNPs on the surface was formed. It provides a simple, rapid, cost-effective way for synthesizing dense monolayer of nanosilver SERS-active substrates. While the SERS-active substrates were used in detection of malachite green (MG), the intensity of SERS-active substrates and concentration have a good linear relationship in the ranges of 10-5M-10-9M, indicating that the substrates have a very satisfied detection on standard sample of as well as actual sample.In the chapter 3, a larger area dense monolayer of nanosilver SERS-active substrates were prepared on the basic of the method reformed from chapter 2. With the CTAB shrinking during drying, a portion of solid phase substrates were exposed. After repeatedly self-assembly, we have successfully synthesized dense monolayer of nanosilver SERS-active substrates. The sensitivity of SERS measurement have shown that the the EF were enhanced with the increase of the number of assembly, and reach up to 1.82×105. This result shows that the ideal SERS substrate composite with good uniformity is the basis of quantitative analysis. Contrast to the substrate in chapter 2, this subtracts more sensitive. Even though the MG concentrations as low as 10-11M.In the chapter 4, Ag@SiO2 Core-shell nanoparticles with two different sizes have been synthesized and characterized by UV and TEM. The shrinking of CTAB and thickness of shell may control the distance of nanosilver in preparing SERS substrate, further influence the nanoparticle gap. SERS substrates, which serve as detection on food safety of crystal violet (CV), were selected based on their active. The intensity of SERS-active substrates and concentration has a good linear relationship in the ranges of 10-5M-10-9M, indicating that the substrates have a very satisfied detection on standard sample as well as actual sample.