Degree

Doctor of Philosophy (PhD)

Department

Chemistry

Document Type

Dissertation

Abstract

Colloidal noble metal nanoparticles are of extreme interest as nanomaterials and for the wide variety of their possible applications in nanomedicine. The unique linear and nonlinear optical processes associated with these nanomaterials can be studied using a variety of spectroscopic techniques including extinction, second harmonic generation (SHG), and two-photon fluorescence (TPF) spectroscopy. In order to better understand and optimize these nanomaterials for their desired applications, it is important to investigate the growth and photophysical dynamics associated with gold nanoparticles, silver-gold core-shell (Ag-Au CS) nanoparticles, and gold-silver-gold core-shell-shell (Au-Ag-Au CSS) nanoparticles in addition to how their size, surface morphology, composition. and other attributes impact the properties exhibited. The use of a multi-faceted approach that combines linear and nonlinear spectroscopic methods with nanoparticle characterization techniques allows for a comprehensive analysis of nanoparticles for a variety of nanoarchitectures and compositions. Transmission electron microscopy (TEM) images at various times during the nanoparticle growth process show that the surface morphology becomes increasingly smoother and more uniform with time, which corresponds to blue shifting and spectral narrowing of the plasmonic peak along with lowering of the SHG and TPF signals. Comparison of the experimental extinction spectra with the Mie theory theoretical simulations show excellent agreement for nanoparticles with smooth, spherical, and ideal nanoarchitectures, while deviations are observed for nanoparticles with non-ideal, urchin-like surface morphology. Preliminary studies of the time-dependent TPF signal provides complementary information to that provided by extinction and SHG spectroscopy on the bulk and surface properties of the nanoparticles, respectively. This intricate approach provides the ability to investigate various growth dynamics of monometallic and bimetallic nanoparticles in real time.

Date

8-24-2026

Committee Chair

Haber, Louis H.

LSU Acknowledgement

1

LSU Accessibility Acknowledgment

1

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