C层包覆Ag纳米颗粒基底的表面增强拉曼散射研究

Ag纳米结构是最常用的表面增强拉曼散射(SERS) 活性基底,缺点是Ag的化学稳定性和 生物相容性比较差。为此,利用化学方法合成了一种新型的SERS活性基底—纳米碳层包覆的 Ag(Ag@C)纳米颗粒。利用透射电子显微镜(TEM)和紫外- 可见吸收光谱对制备的核壳结构纳米颗粒进行了表征,并研究了颗粒的SERS活性。结果表明 ,罗丹明6G(R6G)、结晶紫(CV)和孔雀石绿(MG)分子在Ag@C悬浮液中的SERS光谱强度 与在Ag胶中的SERS光谱强度相比显著增强。根据光谱 的变化规律推断,额外的增强来自于化学增强。由于C层的存在,相比于Ag纳米颗粒, Ag@C颗粒的化学稳定性和生物相容性都有所改进。     

Fabrication of a network structure SERS substrate and the application in ultra-sensitive crystal violet detection

A network structure surface-enhanced Raman scattering(SERS)-active substrate is fabricated by adding Ag sol dropwise on adhesive tape.Scanning electron microscope(SEM) is employed to characterize the structure of the as-prepared substrate.The substrate shows great SERS enhancement ability and good uniformity by using p-aminothiophenol(PATP) as probe molecules.The detection of crystal violet(CV) in aqueous solution is demonstrated,and the detection limit is as low as 10-12M with the aid of the substrate.The results indicate that the proposed method is a potential approach for the fabrication of SERS substrates.     

Gold nanoparticles-decorated single silver nanowire as an efficient SERS-active substrate

A novel surface-enhanced Raman scattering （SERS）-active substrate based on Au nanoparticles （AuNPs）-coated silver nanowire （AgNW） is obtained by an effective and simple method. The results show that the hybrid structures prepared by this method are powerful SERS-active substrates for the detection of malachite green （MG） molecules with the limit of 1 nmol/L. The excellent enhancing, ability mainly comes from two kinds of hot spots. One is from the gaps among the adjacent AuNPs, and the other is the presence of zone between AuNPs and AgNW. In particular, the AuNPs-coated AgNW can be viewed through the objective of the confocal Raman spectrometer due to the length of the AgNW reaches microns, which can improve the repeatability of detection. Moreover, it is of great significance in research of SERS mechanism and application.     

点光源条件下迈克尔逊非定域干涉条纹的分析

迈克尔逊干涉仪常用于观察分振幅干涉条纹,但极少有人对条纹线型进行严格的分析讨论。笔者对点光源条件下迈克尔逊非定域干涉条纹的空间曲线方程进行了计算和分析,得到圆、椭圆、抛物线、双曲线和直线5种形式的条纹线型。进一步对产生不同线型的原因进行了分析计算,证明出现何种条纹与2个平面反射镜中虚光源的相对方位有关。     

Fabrication of silver nanoparticles decorated anodic aluminum oxide as the SERS substrate for the detection of pesticide thiram

An ef?cient surface-enhanced Raman scattering (SERS) substrate is developed based on silver nanoparticles decorated anodic aluminum oxide (Ag/AAO). The AAO templates were fabricated using a two-step anodization approach, and silver nanoparticles (AgNPs) were obtained by thermal decomposition of Ag nitrate in AAO. The structure of Ag/AAO hybrid substrate is characterized by scanning electron microscopy (SEM). The results show that the as-prepared SERS substrates consist of high-density AgNPs with sizes of tens of nanometers. The AgNPs are adsorbed on the surface of AAO template in the form of network structure which is called “hot spot”. The SERS enhancement ability of the nanostructure is verified using thiram as probing molecules. The limit of detection is as low as 1×10-9 mol/L. The results indicate that the as-prepared substrate possesses excellent SERS sensitivity, high stability and uniformity enhancement.