Fabrication and characterization of surface nano-structures for surface enhanced raman scattering

Abstract

My main research interest for my graduate studies was to fabricate nanostructures and characterize its optical response. For my Ph. D thesis work, I have fabricated hot spot structures and void chain structures which is the complimentary to the linear nanodisk chain structures. To investigate plasmonic optical response, I have investigated two-photon photo luminescence and found the confined optical fields for void chain structures. For hot spot structures, I have found great sensitivity for the surface enhanced Raman signal from absorbed molecules. The thesis consists of three chapters. Summaries of each chapter are as follow.

Large Area and Low Cost Fabrications of the 2D Highly Ordered Hot Spot Sites for SERS Applications Several types of hot spot structures were fabricated in the hole sites by simple fabrication steps. In hole sites, different kinds of hot spot structures are formed. Unlike hexagonal close-packed structures, these hot spot structures are individually arranged and orderly exist. For these structures, we observed highly sensitive electromagnetic field enhancements in surface enhanced Raman scattering signals. For the study of electromagnetic field enhancements from linear line chain of nanospheres, we simulated surface electromagnetic field distributions by using finite difference time domain (FDTD) method. For different chain length, we found that field enhancements show different values. By this study, we expect linear chain structure will give more enhanced fields.

Confined Optical Fields in Nanovoid Chain Structures Directly Visualized by Near-Field Optical Imaging Linearly aligned Au nanovoid chain structures were fabricated individually on the glass substrates. These individual structures form linear chains from single void till decameric void chains. Two-photon photoluminescence imaging techniques reveal the localized surface plasmon distributions from the individual structures by using apertured-type home-built near-field sc...