Research On Synthesis And Optical Properties Of Gold Nanorod-based Nanostructures

Noble metal nanomaterials?especially,gold and silver?have become one of hot topics in nanoscience,due to their stable physical properties and unique optical properties,i.e.local surface plasmon resonance?LSPR?.Among the metal nanoparticles,gold nanorods?GNRs?attract much attention in biomedical science,photoelectric technology,et al.,for their unique anisotropy and tunable SPR characteristics depending strongly on their morphology.This dissertation focuses on GNRs synthesis,and further to discuss self-assembly and core-shell structures based on GNRs.FDTD calculations are also utilized to analyze the parameters effect on the SPR of GNRs.The results lay the foundation for the GNRs-based research and applications.The main work and some results included in this dissertation are as follows:1.Monodispersed GNRs colloids with different aspect ratio are synthesized by the seed-mediated growth method,and corresponding SPRL absorption spectrum can be tuned in near infrared region.The effects of the surfactant,reductant and temperature on the growth of the GNRs are investigated.The relationships between the SPRL peak and aspect ratio?AR?are theoretically discussed by FDTD method.The theoretical results agree well with the experimental data,indicating a linear relationship between the SPRL position and AR of AuNRs.2.Side-by-side?S-S?and end-to-end?E-E?assembled Au NRs were obtained with the presence of THF and MPA,respectively.The concentration of additions and reaction temperature would influence on the assembly of the GNRs.The SPR properties of S-S and E-E oriented assemblies were simulated by FDTD solutions.It can be obtained that the shifting SPRL from the theoretical simulation is accordant with that of experimental evolution.3.The sol-gel method is introduced to synthesize the GNR@SiO₂ core-shell structure with different shell thickness,and the formation mechanism of the SiO₂ shell under alkaline condition is discussed.It is the key point in the coating procedure that the concentration of CTAB must be adjusted above the critical micelle concentration.It could be found both theoretically and experimentally that the SPRL of GNR@SiO₂ nanoparticles redshift with the increase of shell thickness.In the further study,a simple and effective way was developed to synthesize soluble and stable GNRs-based assembly of core-shell composite nanostructure,in which the core structures have both E-E and S-S assembled GNRs.The kind of nanostructures not only possessed the SPR property of GNRs assembly,but also kept the thermal stability and biocompatibility.4.Bimetallic nanoparticles Au@Ag and Au@Pd are synthesized experimentally through the overgrowth of GNRs.Absorption spectra of these nanostructures indicate that morphology feature,the degree of polymerization,the media refractive index,and the composition of nanoparticles have significant influence on the SPR property of bimetallic nanoparticles.