The Reach Of Light Absorption Characteristics By Mental Nanostructures

Optical properties of metallic nanostructures are very hot in today’s nanoscienceresearch. Surface-enhanced Raman scattering (SERS) of Metallic nanoparticles showedgreat value in practice since it made tremendous progresses in medical diagnosis,treatment and biochemical sensing. The surface-enhanced Raman scattering derivedfrom the characteristics of the metallic nanoparticle surface plasmon (SP). The surfaceplasmon resonance peak can be adjusted in visible light wavelength through changingthe particles’ shape, size, components or structure. And that is the theoretical basis forproduction of high-tech nanoscale devices.This thesis mainly quantitatively studied the optical properties of bimetalliccore-shell structure. With the help of finite element method for multi-physics couplingsimulation software (COMSOL), we aim to explore the influences of shape, size,core-shell ratio and the change of the dielectric environment on nanoparticles surfaceplasmon resonance characteristics. The paper’s main contents are as follows:In the first chapter, research background and status has been introduced. Through alarge number of readings, I summarized the basic properties of metallic nanostructuresand their applications, which demonstrated the research of metallic core-shell structurenanoparticles is valuable..In the second chapter, the optical principle of metallic nanoparticles is described.Metallic surface plasma theory was introduced in detail. Then I analyzed the metaldielectric constant model, studied the bimetallic core-shell structure’s surface plasmonresonance properties using the scattering theory, and discussed the silver/gold nano farfield effect of core-shell structure. In the middle of discussing numerical calculationmethod of the metal nanoparticles, the finite element method which is a key point in ourfollowing simulations has been specially demonstrated. At last, I briefly introduced thephysical field coupling simulation software used in my thesis COMSOL.In the third chapter, a composite metallic nanostructure, including the shape ofdiamond and cross star, has been designed. With the aid of finite element method, Istudied the factors of the shape and size which remarkably influence surface plasmon resonance properties of the particles, and summarized their relations. Further, theseresults illustrated that SPR peak is adjustable in visible light wavelength. A scientificbasis and theoretical guidance for future application has been provided.In the fourth chapter, the research focused on the metallic structure of core-shellratio, as well as the refractive index of medium environment, which effect on the plasmaresonance characteristics.The results of this paper are as follows: by using finite element method toestablished FEM simulation model. Calculation the quantitative of a new type ofcore-shell nanostructures metal diamond optical parameters. Change its size, shape andthe surrounding dielectric constant of its optical properties, has been optimizedcore-shell structure and more accurate results.By using finite element method, this thesis numerically studied the opticalproperties of different structure, shape, and variety medium index, then summarized therelationships between structure parameters and optical properties. Based on theconclusion, we got accurate numerical results and optimized structure.