Chemistry and Chemical Biology ETDs

Publication Date

Summer 7-27-2019

Abstract

Plasmon on metal nanoparticles can efficiently confine, amplify light at the nanoscale. This property is beneficial for different applications such as harvesting energy of the broad solar spectrum, highly sensitive spectroscopy, photocatalysis, and many other optoelectronic applications. For plasmonic applications, it is necessary to understand the fundamental physical properties of the individual, coupled plasmonic nanomaterials, and their interaction with the surrounding environment, which is not fully understood yet. In this dissertation, the chemical and optical interaction in plasmonic interfaces has been investigated. Plasmon-enhanced photochemistry of p-aminothiophenol as a model molecule is investigated using highly sensitive surface-enhanced Raman spectroscopy (SERS). The result shows the effect of different surface ligands of gold nanorods can change in hot-electron dynamics and catalyze the reaction selectively with varying the pathways of reaction. The optical response of colloidal gold nanorods (AuNR) with gold film (AuF) is studied by measuring the single-particle scattering of plasmonic nanoparticles using dark-field optical microscopy. The experiment reveals that the charge transfer plasmon mode dictates the scattering cross-section of colloidal gold nanorods directly placed on gold film and this mode is independent of the shape and size of the nanoparticle. Distance-dependent interaction of gold nanorods (AuNR) with gold film (AuF) is studied by using the layer-by-layer assembly of polyelectrolytes as well as transparent colloidal quantum dots film as a spacer layer. The photoluminescence and scattering property are measured alternatively of individual gold nanorods coupled to gold film. We experimentally demonstrated that light from a dielectric nanocavity couple out to far-field via both elastic and inelastic scattering processes. The later part of the dissertation focuses on the assembly of plasmonic and excitonic nanoparticles on surfaces. Droplet evaporation at a temperature higher than room temperature is shown as a simple and reproducible method for creating a monolayer of AuNR on different substrates. The assembly of AuNR is characterized using SEM and dark field optical microscopy. Finally, the self-assembly (using the Langmuir-Blodgett, LB technique) and stability study of near infrared emitting colloidal CdSeTe/ZnS alloyed quantum dots are presented. Photoluminescence and elemental analysis indicate that interatomic diffusion leads to crystal transformation upon exposure of the nanocrystals to ambient conditions.

Language

English

Keywords

Plasmon, Dark-field, Photochemistry, Near field, Gold nanorods, Surface enhanced Raman Spectroscopy (SERS)

Document Type

Dissertation

Degree Name

Chemistry

Level of Degree

Doctoral

Department Name

Department of Chemistry and Chemical Biology

First Committee Member (Chair)

Terefe Habteyes

Second Committee Member

John Grey

Third Committee Member

Yang Qin

Fourth Committee Member

Alejandro Manjavacas

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