| This dissertation presents research on the synthesis of anisotropic and multicomponent nanoparticles by liquid-phase approaches. Nanoparticles have attracted broad attention from researchers in various fields for both their fundamental size-dependent properties and their many potential applications. These nanomaterials exhibit size and shape-dependent characteristics, including novel electronic, magnetic, optical, chemical, and mechanical properties that cannot be achieved using their bulk counterparts. In general, the content of this dissertation can be divided into three main categories, which is fabrication and characterization of metal nanoshells, shape control of gold nanorods, and morphology control of semiconductor nanoparticles.; Advanced nanomaterials derived from core-shell composite particles are of extensive scientific interest, due to their unique and tailorable properties for various applications. Metal-coated colloidal core-shell nanocomposite particles have potential applications as catalysts, components of sensors, and substrates for surface-enhanced Raman scattering. In the first part of the dissertation, a general strategy to prepare metal nanoshells on the surfaces of monodispersed polystyrene microspheres has been developed. By systematically engineering the dimensions of the core and shell, the surface plasmon resonance of the nanoshell can be tuned across the visible and the near-infrared regions of the electromagnetic spectrum. This approach was also extended to produce silver shells on gold nanoparticle cores with similar tunable absorption spectra.; Gold nanorods have received great attention due to their unique size-dependent optical properties that have found uses in optoelectronic devices, gene delivery, bioimaging, and biosensors. Gold nanorods have two distinct plasmon bands, namely, the longitudinal plasmon band corresponding to light absorption and scattering along the long axis of the particle, and the transverse plasmon band corresponding to the same along the short axis of the particle. Generally, the longitudinal plasmon absorption peak of gold nanorods is tunable throughout the visible and near-infrared region of the spectrum as a function of size, shape, aggregation state, and local environment of the particles. It is well established that the maximum of the longitudinal band red shifts with increasing aspect ratio. In this dissertation, we have systematically investigated the effects of additives on the formation of gold nanorods. (Abstract shortened by UMI.)... |
