| We have successfully synthesized silver halide and gold/silver halide nanorods within the pores of a host anodic aluminum oxide matrix. We have characterized them using TEM and XRD, and investigated their optical properties using UV/visible spectroscopy. The formation of the silver halides (AgI and AgBr) was a two step process that required the deposition of silver metal followed by an electrochemical oxidation with the appropriate potassium halide solution. Au/AgX heterojunction rods were also synthesized electrochemically.; Transmission electron microscope images were taken of all our composite systems. TEM images of Au/AgX both inside and extracted from the host matrix indicated the formation of long rods. However, we could not differentiate between the metal and semiconductor phases, although the rods were significantly longer than Au only nanoparticles.; Optical characterization of Au/AgI composites suggested that there was an interaction between the gold and silver iodide phases. Spectra of Au/AgI heterojunction nanoparticles exhibited an Au plasmon resonance that was broadened and red shifted more than expected. Theoretical simulations using the pair particle polarizability model could not simulate experimental data, except when a model for mixing was included in the simulation. The mixing is thought to be on the atomic level. Nanocomposites containing Au/Au2S/AgI were also synthesized to look at the effect of the addition of a layer that acts as a barrier to mixing. Spectra of such samples showed a narrow blue shifted Au plasmon, but the AgI exciton did not reappear.; Crystallinity and crystal structure of our nanoparticle composites were examined using X-ray powder diffraction techniques. XRD data suggests that we have prepared highly crystalline nanoparticles within our amorphous host matrix. AgI composites exhibited some preferred orientation within the pores that increased upon annealing. High levels of preferred orientation was observed for Au/AgI composites. This was investigated by measuring pole figures for the (002) reflection, for as-deposited AgI, annealed AgI, Au/AgI and Au/Au 2S/AgI systems. These figures seem to indicate alignment of the c-axis of the hexagonal morph along approximately the pore direction, initiating fiber formation. (Abstract shortened by UMI.)... |
