Year

2021

Season

Spring

Paper Type

Master's Thesis

College

College of Computing, Engineering & Construction

Degree Name

Master of Science in Mechanical Engineering (MSME)

Department

Engineering

NACO controlled Corporate Body

University of North Florida. School of Engineering

First Advisor

Dr. Stephen Stagon

Second Advisor

Dr. Grant Bevill

Rights Statement

http://rightsstatements.org/vocab/InC/1.0/

Third Advisor

Dr. Jutima Simsiriwong

Department Chair

Dr. Osama Jadaan

College Dean

Dr. William Chip Klostermeyer

Abstract

The nanoscience and nanotechnology community have a common goal in better understanding the surfaced enhanced Raman scattering (SERS) that occurs due to laser plasmon resonance in conjunction with metal enhanced substrates. Metallic nanostructures, such as silver (Ag) nanorods, are widely used in biological and chemical sensing applications that rely on the measurement of subtle changes in the optical response of the nanostructures in the presence of a target agent. The optical response of Ag nanorods and most other metallic nanostructures is highly sensitive to morphology and surface chemical termination. In pristine condition, the optical properties of Ag nanorods and other metallic nanostructures are well documented in the literature. However, almost nothing is known of the structure – property effects of exposure to solvents, buffered solutions, and similar in real applications. This document reports on the investigation into the effects of dissolved gasses, which are known to corrode bulk and thin film silver (Ag), in di-ionized water on Ag nanorods. Through SEM, SPM, UV-Vis, and Raman Spectroscopy, characterization of rapid corrosion and morphological changes are observed within minutes when Ag nanorods are exposed to water with dissolved gases present. Conversely, almost no measurable changes are observed when the dissolved gases are removed from the water via boiling. The current research attempts in exploiting the enhancement factors of optical properties dealing with SERS. Growing substrates to examine in SERS by using physical vapor deposition (PVD) on corning glass depositing Ag nanorods will enlighten the nanoscience and nanotechnology community on these changes in optical properties. SPM and SEM images both show significant differences through corrosion of Ag on the two different types of water. The species from corrosion in regular water appears to be AgO, as there is no Sulphur detected by the SEM’s EDS spectrum. KFM shows clear differences in surface potential indicating a chemical change. UV-Vis shows a decrease in resonance and absorptivity after corroding. The goal of this investigation is to characterize oxidation species grown on the Ag nanorods when the substrate is exposed to O and dissolved gasses. Raman Spectrum shows that for a fluorescent molecule (R6G), the overall measured Raman signal significantly increases with oxidation due to activation of surface enhanced fluorescence. Statistical T-test were run on spectrum, a value of 1.83E-05 was accessed to prove the significant increase in signal. When oxidation occurs from substrates stored in water with dissolved gases like the R6G samples, the scatter in the signal also significantly increases, proven with an f-test value of 4.76E-05. Additionally, when a non-resonant molecule is used, like our caffeine, the scatter in signal significantly increases, proven by f-test value of 2.4E-02. By experimenting contrasting substrate-samples during Raman that were taken straight out of vacuum or stored in water, the community can see the indicating affect measured in Raman spectra.

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