Preparation And Application Of Surface Enhancement Raman Scattering Substrates Based On Noble Metal

As a analytical technology, surface-enhanced Raman scattering(SERS) has someadvantages such as high sensitivity and repeatability, good selectivity, non-destructiveand the in-situ detection ability. SERS has been widely used in component detection,environmental sciences, biological medicine and sensors in the past decades. One ofthe key point of SERS is the its substrates. Nevertheless, creating high-enhancement,large scale and reproducible substrates through inexpensive and high-throughputmethods still remains a challenge. Noble metals, such as Ag, Au and Cu, have beenwidely used as SERS-active substrates owing to their strong localized surface plasmonresonance (LSPR) under most of the commonly-used lasers. Finite-differenttime-domain(FDTD) is one significant method to study the distribution ofelectromagnetic field in space, which is widely used in the simulation of SERS. In thispaper, we prepared SERS active substrates based on noble metal, and simulated theirenhanced ability of electric field intensity through FDTD method. The main researchesare as follow:(1) Au nanoparticles were in-situ grown on Ge wafer through a Galvanicdisplacement. The average diameter of the Au particles was14nm, with a3.6nminterspace distance. The as-prepared Au-Ge substrate showed good SERS activity andrepeatability in the detection of1×10-8M R6G solution. The Raman enhancementfactor was calculated to be3.44×106. The relative standard deviation (RSD) values ofthe main vibrations peaks were all below20%. FDTD simulation was performed toevaluate the electric field enhancement ability of the as-prepared Au-Ni substrate. Boththe experiment and the simulation showed this Au-Ge material was a good SERSactive substrate.(2) Use a Galvanic displacement reaction, Au nanoparticles were grown on Niand NiO/Ni substrates, respectively. With the increasing of reaction time, the size and desity of AuNPs were both increased. The sample prepared in60min had the optimalmorphology and distribution. Both the two substrates showed excellent SERSsensitivity and repeatability in the detection of R6G solution. Compared with Au-Ni,Au-Ni/NiO one had a better uniformity of SERS signal. This may be that the AuNPsgrwon on NiO/Ni substrate were smaller than those on Ni, which produced more hotspots, leading a low randomness. In the FDTD simulation, we discussed the effects ofAu particles’s size and NiO’s thickness to the the enhancement ability of electric field.(3) AgVO3nanobelts were synthetized through a hydrothermal method. Underγ-ray irradiation, Ag element was reduced into Ag nanoparticles on the surface of thenanobelts. By changing the dose of γ-ray irradiation, Ag/AgVO3nanobelts withdifferent content of Ag were prepared. These materials were use in the detection ofR6G molecule. Compared to AgVO3nanobelts without any irradiation, the as-preparedAg/AgVO3nanobelts showd a better SERS enhancement ability.(4)3D-FDTD was performed to simulate the electric field distribution aroundnoble metals. First, we discussed the difference of noble metals located on Ge and Sisubstrates. The result showed that metals located on Ge had a larger electric fieldintensity than that on Si. Then we studied the effect of particle size and gap distance tothe enhancement ability of electric field. With the increase of particle size and thedecrease of gap distance, the electric field intensity between noble metals particlesincreased. Last, we investigated the enhancement ability of electric field in multilayerAu array.