Screening, Coulomb Interactions, and Plasmonic Phenomena on the Nanoscale

With the advancement of nanotechnology in various fields of science and engineering, the lifestyle of human being has changed dramatically in good ways. However, due to the fact that everything is so small in nanoscale, it is very hard to study phenomena that would be very interesting. In this dissertation, optical, plasmonic, electrolyte properties of nanostructures and theoretical and experimental characterization methodologies are presented. First, the plasmon assisted optical absorption in silicon nanowire is studied. Recently, it was shown that a silicon nanowire coated with silver can produced hot luminescence which would have been very hard to happen with silicon by itself because silicon is an indirect bandgap material. We propose possible mechanisms that make the optical absorption in silicon possible, which eventually leads to hot luminescence. The results show qualitative agreement with experimental results reported in the literature. Second, numerical simulations were performed using an open source finite different time domain (FDTD) simulator, meep, to study the plasmonic properties of non-precious metals like copper, nickel, and aluminum as a replacement of a precious metal, silver. The scattering cross section calculations show the non-precious metals can be as effective as silver in the visible region. Finally, a method of synthesis ZnO quantum dots (QDs), characterizations of various properties of ZnO QDs, techniques to immobilize and measure electrostatic force of QDs, and their effect on ion currents of a neuronal cell are presented. Our results show that the quantum dots that produce electrostatic field can affect the ion channel dynamics that can lead to many applications.