Electronic Theses and Dissertations

Saghar Gomrok

Date

2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Chemistry

Committee Chair

Yongmei Wang

Committee Member

Xiaohua Huang

Committee Member

Thang Ba Hoang

Committee Member

Daniel R Nascimento

Committee Member

Xiao Shen

Abstract

Plasmonics is a multidisciplinary field focused on the study of collective oscillations of conduction electrons in metals, known as plasmons. These plasmons lead to unique optical responses when coupled with nanostructures, enhancing electric fields at the metal surface at specific wavelengths. Surface plasmon resonance (SPR) occurs at the interface of metal-dielectric structures, while localized surface plasmon resonance (LSPR) manifests within metallic nanoparticles (NPs), influenced by composition, size, shape, and surroundings. Gold (Au) and silver (Ag) NPs are well-known for distinctive LSPR-induced optical properties. Assemblies of Au or Ag metallic NPs allow further tuning of plasmonic behaviors. Moreover, packing metallic NPs in multimeric structures produces enhanced electric fields (hot spots) that are crucial for Surface Enhanced Raman Spectroscopy (SERS) detection. This dissertation investigates NP assemblies of varying sizes, compositions, and orientations to better understand their role in optimizing SERS signals. The study uses computational methods like Mie theory and the discrete dipole approximation (DDA) to understand plasmonic properties of these structures. The study reveals how the position of a NP in the arrangement affects its contribution to the near-field enhancement in a multimer structure. Additionally, it explores the coupling of NPs made from different materials to broaden the understanding of spectral and functional capabilities of plasmonic structures. The study also examines how gold NP assemblies with different geometries respond to changes of incident light orientations, with the goal to design systems that have more stable SERS signals under different light orientations. The results presented in this dissertation can provide insight on how to modify plasmonic structures to meet the needs for specific applications.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to ProQuest.

Notes

Open Access

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