Synthesis, theoretical calculation, and applications of plasmonic nanowires.

Abstract

Silver nanowires with well-defined dimensions are particularly interesting to be investigated because bulk silver exhibits the highest electrical (or thermal) conductivity among all metals. Silver has also been used in a rich variety of commercial applications, and the performance of silver in these applications could be potentially enhanced by processing silver into 1D nanostructures with well-controlled dimensions and aspect ratios. For instance, the loading amount of silver in a polymeric composite could be significantly reduced when nanoparticles of silver are replaced by nanowires having higher aspect ratios. A number of chemical approaches have been actively explored to process silver into 1D nanostructures. However, to the best of our knowledge, there has yet to be any reports on rational methods to control nanowire diameters and corresponding physical properties. In chapter 1, we report the thickness control of silver nanowires using different sized gold seeds, resultantly forming Ag-Au-Ag heterometallic nanowires. Ag-Au-Ag heterometallic nanowires were synthesized via a seed-mediated process from Au decahedral seeds with different sizes. The diameter of the Ag-Au-Ag nanowires is precisely controlled in a range of 60-150 nm by using gold decahedral seeds with corresponding edge sizes. The structures of the Ag-Au-Ag heterometallic nanowires have distinguishable Au and Ag segments in their EDX, line profile, and elemental mapping analysis. The three transversally excited bulk, localized, and propagating modes of the Ag-Au-Ag heterometallic nanowires exhibit optical signatures in the UV-vis spectra. In particular, the end-on incidence propagating mode is highly sensitive to the nanowire diameter. These three transversally modes were analyzed by a DDA (Discrete Dipole Approximation) calculation method. With the development of nanotechnology and biotechnology, the devices have become smaller and more complex, and they must have identification codes for appl...