Modulation Of Surface Plasmon Resonance, The Shape Of The Metal Nanoparticles

The optical properties of metallic nanoparticles and their application in surface enhanced Raman scattering (SERS) have been a hot topic in nanoscience and nanotechnology. Because nanoparticles are different from bulk materials in the construction, nanoparticles bear some effects, for example, quantum size effect, small size effect, surface effect and so on. These basic properties lead to special optical properties - surface plasmon resonance. The surface plasma resonance peak positions is influenced by the size, shape, metal composition and surrounding medium, the special properties can apply in many areas.The main focus of this thesis is to surpass the limitation of Mie theory, whose application is rigorously limited to spherical particles, in order to theoretically study the quantitative dependence of the linear optical properties and electromagnetic enhancement mechanism of SERS on the size, shape, surrounding medium of metal nanoparticles with arbitrary shape.The main work of this paper is summarized as follows.1. Based on the surface plasmon resonance (SPR) properties of metal nanoparticles, the transmission characteristics of a metallic film with subwavelength ellipsoid nanohole arrays are investigated by using the three-dimensional finite-difference time-domain (3D-FDTD) method. The influences of the lattice constant and the hole shape on the transmission are studied. The extraordinary transmission is attributed to the collaboration of localized waveguide resonance and SPR.2. Optical properties of metal nanoparticles are influenced by the metal composition, shape, size, polarization direction of light and effective index of the medium around the nanoparticles. The plasmonic properties of rhombus, cross-shaped silver nanoparticle and arraies are investigated using 3D-FDTD method. Then summary the variation of these nanoparticles and arraies.3. More detailed calculation of electric fields (E-fields) distribution and the maxtium field enhancement factor (EF) of nanoparticles based on the 3D-FDTD method, with consideration of the size, shape, medium environment and interparticle-coupling effect. The"hot spot"with huge SERS activity of nanoparticles that is of increasing in single molecular SERS is also discussed.