Plasmonic nanostructures : fabrication, optical properties and anti-counterfeiting application
Date of Issue2017
School of Physical and Mathematical Sciences
This thesis involves my four-year graduate research studies on fabrication, optical properties and anti-counterfeiting applications of plasmonic nanostructures. In the beginning, recent works are summarized focusing on synthetic methods used to engineer the morphologies, parameters used to tune the plasmonic properties and applications of plasmonic nanoparticles (chapter 1). Two challenges are generalized in the field of plasmonic nanostructures: (i) to efficiently tune and understand the surface plasmonic properties of plasmonic nanoparticles at single-particle level and in the coupled system; (ii) to develop novel platforms using plasmonic nanoparticles for practical applications. Based on that, I aim to efficiently enhance the intensity and enlarge the densities of hot spots on individual plasmonic nanoparticles via precision synthesis (chapter 2), to understand the plasmon resonances that occur in the Ag nanocube dimers (chapter 3) and to develop plasmonic anti-counterfeiting platforms on both rigid (chapter 4) and flexible substrates (chapter 5). We efficiently increase the volumes and intensities of localized fields on individual nanoparticles by introducing a “hot spots over hot spots” strategy that selectively depositing plasmonic active nanodots on edge and tip hot spots regions (chapter 1). Moreover, combining CL and EELS maps on Ag nanocube dimers, we acquire knowledge on localized surface plasmon resonances (LSPRs) that occur in Ag nanocube dimers and diretly visualize how plasmon modes evolve with alteration of dimer orientations with nanoscale spatial resolution (chapter 3). Besides, we broaden the applications of plasmonic nanoparticles by introducing a novel anti-counterfeiting platform encoding five identifying layers in the form of SERS, fluorescence and their signal intensities on a single platform (chapter 4). We also develop a flexible plasmonic anti-counterfeiting platform giving stable SERS readouts over applying several cycles of external bending forces for practical applications (chapter 5). In the end, outlook of these research works in this field is proposed (chapter 6).