SERS Properties Of Several Metal Nanoparticle Dimers

Surface enhanced Raman scattering（SERS）technology is a new type of high-sensitivity spectral detection and analysis technology.It can accurately provide the“fingerprint”infor-mation of the detected samples.In recent years,it has been widely used in the detection field of ultra-low concentration and even monomer solutions.Since the emergence of SERS technology,various nano SERS structures made of precious metal nano materials have be-come a research hotspot in the fields of material science,medicine,environmental analysis,biomolecular detection and so on.Good detection limit and spatial resolution have also been achieved in the experiment.However,the theoretical exploration of the formation mechanis-m of SERS spectrum and the optimal design of substrate materials and configurations need to be further explored and studied.In this paper,several typical metal dimer nanostructures and materials are configured through high-precision theoretical calculation,and their SERS effects are systematically calculated and simulated.The conclusions provide guidance for the experimental research in this field,so as to promote the development of the research field of SERS properties of metal nanoparticles.The research contents are as follows:Firstly,Al₂O₃ shell was wrapped on the basis of Au spherical dimer to study its SERS performance.First of all,by calculating the electric field enhancement effect of Au spherical dimer at different incident light angles,different radius and different distances between the dimers,the optimal Au spherical dimer configuration was obtained.Secondly,the surface is covered with a layer of Al₂O₃,and the electric field enhancement is calculated by changing the thickness of Al₂O₃shell layer.And the effect of Al₂O₃shell on electric field peak po-sition is more clearly indicated by extinction spectrum.Then the enhancement effect of Au spherical dimer with or without shell is compared to obtain a better configuration.Finally,the effects of different excitation wavelengths on Raman enhancement factor of Au spherical dimer with or without shell at the same distance are compared.Thus the systematic study of Au@Al₂O₃core-shell structure is completed.Secondly,the SERS performance and Raman enhanced spatial resolution of Au,Ag,Cu and Al triangular plate dimers（TPD）commonly used in SERS research were studied.First of all,The influence of tip radian of triangle plate,distance between dimers and edge thickness ratio of triangle plate on electric field enhancement factor and peak position was calculated by finite element method.secondly,the electric field distribution diagram and displacement current distribution diagram of TPD are drawn to show the electric field enhancement area of TPD and the comprehensive effect of different coupling modes and lightning rod effect of TPD.Then the spatial resolution of the TPD system is explained by introducing the half height and width of Raman enhancement factor.The last Cr substrate was added to the trian-gular plate configuration for simulation calculation,which made the simulation result closer to reality,thus providing guidance for SERS experiment of triangular plate configuration.