The Study Of The Preparation And The Optical Properties Of Metallic Nanostructures

The study of the optical properties of metal nanoparticle arrays has been a hotspot in the field of surface plasmons.The ordered metal nanoparticle structure,especially the metal nanoshell structure not only has the optical properties of photonic crystals,but also has the optical properties of metal nanoshells.In this thesis,the concept of surface plasmons is firstly introduced.Localized surface plasmon,surface plasmon polaritons,the latest progress and application about surface plasmons are discussed.Secondly,some fabrication methods of metal nanostructures and the related concepts of extraordinary optical transmission are discussed.Finally,two novel fabrication methods of metal nanostructures are innovatively proposed,and their optical properties are analyzed in detail.The content of the thesis mainly includes the following two aspects:1.We present a novel method for fabricating a monolayer of hexagonal-close-packed metallic nanoshells with a small opening,based on a combination of a porous polymer template and a nanocrystal-seeded electroless plating technique.Light transmission spectra of the metallic nanoshell arrays are measured,which show that light can transmit through the dense particle assemblies via excitations of a variety of surface-plasmons(SPs).Further numerical simulations confirm these transmission resonances and reveal that they are attributed to the excitations of localized quadrupolar spherelike and Fano-type hybridized SP modes supported by the specific structure.The present metallic microstructure could find applications in plasmonics.2.We report a facile method for controllable fabrication of high-density silver nanoparticle films with a widely adjustable surface plasmon resonance(SPR)frequency,based on the gas phase cluster beam deposition.On the one hand,we can control the particle size by depositing clusters on silica substrate.Light extinction spectra of the self-assembled Ag nanoparticles with various particle sizes are characterized and show two SPRs,in which a SPR exhibits a redshift from less 400 nm to more than 570 nm with an increase in the particle size,whereas the other shows a slight position shifting.On the other hand,the inter-particle distance of the self-assembled Ag nanoparticles can also be controlled by depositing clusters on silica glass coated with Formvar film,and the SPR wavelength shows a redshift from 400 nm to more than 560 nm,which can be attributed to the increase of the fraction of closely spaced nanoparticle pairs that are near-field coupled with the deposition mass.The size and coverage-dependent SPR properties are also compared with the resultsfrom the discrete dipole approximation calculations.The present method of tailoring metallic microstructures could find important applications in plasmonics.