Syntheses Of Plate-like Silver Nanostructures And Investigation Of Their Surface Plasmon Resonance

Metals with size in nanometer scales usually possess properties distinctfrom those of their bulk or single atom and can be applied in catalysis,biotechnology, magnetics, electronics, optics, etc. It has been provenexperimentlally and theoretically that the size and shapes of the nanosizedmetallic particles influence the properties remarkably. And developing newmethods for the syntheses of nanomaterials with different morphologies hasbecome one of the focuses of the nanoscience. In addition, theoreticalinvestigation is necessary to present a deep understanding of the essence.Therefore, this dissertation contains such two parts:First, we fabricated two-dimensional staggered silver nanoplates byreplacing the inert substrate with a chemically active aluminium foil in anormal silver mirror reaction. Investigation indicates that the aluminiumfoil can release a trace amount of hydroxide aluminum during the reaction,which induces the formation of oriented silver nanoplates. According to thismechanism, aluminum nitrate was also used in controlling the morphologyof the silver nanoparticles. And the method was finally extended to modifythe polypyrrole microstructures and it was proven to be a general approachof the surface modification.The other part of the dissertation is about the optics of the silvernanoplates. After a detailed introduction of the discrete dipoleapproximation method, we developed a graphic technique based on theresolution of the vector to analyze the dipole lattice in the result. Theextinction spectra of five triangle nanoplates in vacuum with samethickness and various side lengths are simulated under a certain incidentpolarized plane wave. The graphic method was applied to characterize andassign the surface plasmon resonance mode at each spectral peak. Threesurface resonance modes are recognized by this way. The wavelength ofeach surface plasmon resonance mode is linearly dependent on the sidelength of triangle nanoplate, and the result is fairly helpful to theassignment of spectra and the control of fabrication. The attribution of theabsorption and scattering effect to the extinction is also discussed, and thetrend is similar to that obtained from nanospheres. At the last of this part,surface plasmon resonances of triangle nanoplates irradiated by other twotypical incidences are investigated in the same way.