The Study Of The Synthesis Of Low Dimensional Ag Nanostructures And The Properties Of Surface Plasmon Polaritons

The plasmonics has recently been a very active research field based on the variousmetal nanostructures. The technologies of surface-enhanced Raman scattering (SERS)and surface plasmon resonance (SPR) have been studied deeply and applied widely inmany fields. Plasmonic waveguide also possess great potential applications for nanooptoelectronic integration. The work of this dissertation is carried out based on thesynthesis of the silver nanostructures. The surface Raman scattering spectra ofnanostructures and the properties of the propagating surface plasmon polaritons (SPPs)on silver nanowires and Ag-SiO2core-shell nanowires are investigated deeply in thisdissertation. The remote excitation polarization-dependent surface photochemicalreaction by plasmonic waveguide is also studied.First, the silver nanostructures are synthesized by chemically reducing AgNO3withpolyol in this dissertation. The low dimensional uniform Ag nanostructures, such as Agnanospheres and Ag nanowires and Ag nanorices, are obtained under optimal experimentconditions by controling the reactionants concentration, reaction time and speed. Thesilica core shell structure of the silver nanospheres and nanowires are also fabricated bythe sol-gel method.Second, the impact of silica layer on the propagating properties of Ag namowirewaveguide is investigated. The emitting intensity from the end of nanowire is measuredthrough exciting the fluorescent molecules localed on different position of the nanowire.The propagation lengths of surface plasmon polaritons on silver nanowires with differentthickness silica layers can be obtained by linear fitting according to the function ofintensity as the excitation point. The result indicates that the Ag-SiO2core-shellnanowires confine the electromagnetic field stronger than bare Ag nanowire. For glasssubstrate with small refractive index, the propagation lengths of SPPs on Ag-SiO2core-shell nanowires are shorter than that of bare silver nanowires with the samediameter, while they are longer for the silicon substrate with big refractive index.Next, it is proposed and researched that the polarization-dependent surface photochemical reaction can be excited remotely by plasmonic waveguide. SPPs aregenerated at the end of a silver nanowire by incidence light, and propagate efficientlyalong the nanowire. It can be coupled out in photons at the discontinuities of the wirewith nanoparticles or another nanowire as nanoantenna. The remote excitationpolarization-dependent SERS spectra obtained experimentally in the nanogaps of thesystems of nano particles-wire and crossing nanowires reveal the occurrence of surfacecatalytic reaction.Last, the chemical enhancement mechanisms on deep ultraviolet tip-enhancedRaman scattering spectra of anthraquinone in Al3-anthraquinone-Al3junction are studiedwith time dependent density functional theory for plasmon resonance properties ofAluminum in UV range. The results reveal that the Raman spectrum is resonance Ramanscattering, and chemical enhancement is on the order of 107.