| Surface-Enhanced Raman Scattering(SERS)has been widely used in biomedical,environmental monitoring,and food safety,due to it is fast fingerprint recognition and nondestructive testing technology.SERS has been recognized as a mature sensing technology and is constantly evolving.And,the SERS substrate is considered key to SERS technology.However,single noble metal nanoparticles are difficult to realize the functionalization of SERS substrates,so more and more studies have been conducted on metal composite structures as SERS substrates.In this paper,it studied the composite structure of silver nanoparticles coupled with silver films for self-assembly in the preparation of SERS substrates.This structure is used to improve the performance of SERS substrates and the effect of AgNPs’size on substrate performance is studied.The main research content is as follows:Firstly,study the controllable size of silver nanoparticles.Silver nanoparticles were prepared in 10 different sizes using three methods.Firstly,sodium citrate was used to reduce silver nitrate by direct synthesis,resulting in the synthesis of silver particles with a size of 48 nm.Secondly,sodium citrate and L-ascorbic acid were used as reducing agents to reduce silver nitrate,and the volume of L-ascorbic acid was regulated to prepare silver nanoparticles of different sizes.And silver nanoparticles were synthesized with sizes of 30 nm,46 nm,and 51 nm,respectively.Once again,L-ascorbic acid was used as a reducing agent to reduce the silver ammonia solution,and the silver seeds were controlled in different volumes.Silver nanoparticles were prepared by seed reduction method,and the size range of spherical silver nanoparticles synthesized was between 50-200 nm.Finally,the morphology,size,yield,and optical properties of synthesized silver nanoparticles were studied.Secondly,study the self-assembly and SERS properties of silver nanoparticles on substrates.The silver film was sputtered onto the surface of the biological substrate cicada wings.What’s more,the interface self-assembly process was used to assemble silver nanoparticles into densely arranged silver layers at the water oil interface.And the silver layer was pulled and self-assembled onto the substrate surface,resulting in a composite structure of silver nanoparticles and Ag film self-assembly.Silver nanoparticles were characterized by scanning electron microscopy on the surface distribution of the substrate.And the substrate performance was analyzed to determine the changes in SERS performance before and after self-assembly of silver nanoparticles.In addition,simulations were used to analyze the distribution of electromagnetic fields and investigate the changes in substrate electromagnetic field intensity before and after self-assembly of silver nanoparticles.The results showed that the performance of the SERS substrate was improved after self-assembly of silver nanoparticles,the SERS strength was doubled,and the RSD value of the substrate decreased from 12.6%to 6.1%.Finally,a study on the effect of different sizes of silver nanoparticles on the performance of SERS in composite structure substrates.Silver nanoparticles with different sizes were modified on the cicada wings substrate by Magnetron sputtering,and the influence of particle size on the SERS performance of composite substrate was studied.In addition,the surface distribution of silver nanoparticles with different sizes was analyzed under scanning electron microscopy.Raman spectroscopy was used to analyze the SERS performance of the substrate.The results indicated that particle size affected the SERS strength and sensitivity of the substrate.What’s more,AgNPs102/Ag-20/CW substrate exhibited strong SERS enhancement and high sensitivity,and the enhancement factor of AgNPs102/Ag-20/CW substrate can reach 2.22×106.The high particle yield affected the uniformity and reproducibility of the SERS substrate. |
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