Research On Characteristics Of Localized Surface Plasmon Resonance Of Metal Nanoparticles

The metal nanoparticles have completely different optical properties with the bulk metal due to the reason of size. The absorption and scattering of the incident light in a specific wavelength can be enhanced by metal nanoparticles. Because of its unique optical properties, metal nanoparticles have been widely used in biological medical, biological sensing, energy, environment and other fields. In this paper, the resonance optical properties and refractive index sensitivity of gold nanoparticles, silver nanoparticles and gold/silver composite nanoparticles were investigated by Mie scattering theory and double layer concentric sphere Mie theory. The optical properties of three kinds of common metal nano spherical shell structures are studied by using the theory of double concentric spheres Mie scattering. By changing the inner and outer radius of the spherical shell, the optimum absorption efficiency of the spherical shell under the specific incident wavelength is obtained, and the absorption efficiency of the three kinds of spherical shells is compared. In the end, the optical properties of metal nanoparticles and the four gold nanoparticles were studied by using the discrete dipole approximation method. The main research work of this paper is as follows:(1) The change law of extinction coefficient, scattering coefficient and absorption coefficient of gold and silver nanoparticles with the radius and the refractive index of the surrounding environment were studied by Mie scattering theory. The refractive index sensitivity of gold and silver nanoparticles was calculated and compared with that of the same conditions. The optical properties of Au Ag composite nanoparticles were studied using the double layer concentric sphere Mie scattering theory, including the change law of the resonance extinction coefficient, resonance scattering coefficient and the resonance absorption coefficient of gold package silver nanoparticles and silver coated gold nanoparticles with kernel radius, shell thickness and surrounding refractive index, otherwise, the refraction rate sensitivity of the gold and silver nanospheres, gold package silver nanospheres shell and silver coated gold nano spherical shell of were compared under the same conditions.(2) The optical properties of three kinds of common metal nano spheres are studied by using the theory of double concentric spheres Mie scattering. The three kinds of nano spherical shells are the gold nanoparticles of vacuum, polystyrene and silica. The resonance extinction coefficient, resonance scattering coefficient and resonance absorption coefficient of the three kinds of metal nano spheres were analyzed quantitatively according the variation of the core radius, shell thickness and surrounding media. The resonance absorption properties of metal nanometer spherical shell is used in the biomedical application.In order to find the optimal size of the spherical shell to achieve the maximum absorption efficiency, the absorption efficiency of these three kinds of spherical shell is optimized by changing the radius of the spherical shell, and the absorption efficiency of three kinds of spherical shell is compared.(3) The resonant optical properties of metal nanoparticles dimers were quantified studied though Discrete Dipole Approximation(DDA), including the change regularity of resonance extinction coefficient, resonance scattering coefficient and resonance absorption coefficient of dimers structure consists of two gold nanospheres or dimers structure consists of a gold and a silver nanospheres with the change of space between two nanospheres, sphere radius and the surrounding refractive index. Finally we quantitatively analyz the extinction, scattering and absorption spectra of the nano group consists of four nanoclusters which has same radius.