The Preparation And Properties Of Sers Active Substrate For Silver/dragonfly Wings

Surface-Enhanced Raman Scattering(SERS)is a surface enhancement effect with rough surface to enhance the Raman signal.It produces an ultra-high sensitivity,and non-destructive,rapid detection.Thus it has gradually developed as an important tool in surface science,food safety,environmental protection,medical testing and other fields.The performance of the substrate plays a crucial factor in determining the test sensitivity.In order to solve this issue,we simulated the spherical silver nanoparticle structure and the increased electromagnetic field as a result of its attachment to the dragonfly wings.We fabricated a new silver/dragonfly wings biological substrate as well.As a result,we make the SERS preparation process simple and low cost.Our SERS substrate has a better enhancement effect as well.The main content is as follows:First of all,the thesis makes a brief introduction of several common calculation methods involved in calculating the common enhancement factor of the local field.There is a special emphasis on the principle of three-dimensional finite difference time domain method(3D-FDTD).Secondly,this thesis describes the whole preparation process for the silver nanoparticles.We use sodium citrate to restore silver nitrate and thus produces the silver nanoparticles.We change the concentration of silver nitrate or adjust the ratio of sodium citrate and silver nitrate to get different sizes of silver nanoparticles.We test and analyze the nanoparticles through the scanning electron microscopy.On this basis,we complete the preparation for silver/dragonfly wings substrate,and use rhodamine 6G(R6G)as a probe molecule to test the Raman signal of the new SERS active substrate.At last,we use 3D-FDTD method to analyze the electric field of silver nanoparticles with different diameter.We find that both the spherical silver nanoparticles' size and the distance between particles have an influence on the local electric field's enhancement.We then come up with models similar to our silver/dragonfly wings structure.We simulate and calculate the largest local field distribution model for each model to analyze the performance of silver/dragonfly wings substrate from theoretical and experimental aspects.