Computational Investigation of the Optical and Photothermal Properties of Plasmonic Nanostructures

Multifunctional nanomaterials are of high interest to a wide range of technological applications that span across multiple interdisciplinary topics in science such biomedicine, applied chemistry, and optics. Developing such nanomaterials and systems capable to sustain specific functions for a targeted application is a complex task which requires to first understanding the fundamental physical properties and mechanisms that are at play. My focus is on the field of nano-optics (i.e., nanophotonics), and more specifically, Plasmonics. Coherent, collective oscillations of the conduction electron gas, known as surface plasmon resonances, are sustained by nanostructures composed of noble metals such as Au, Ag, Al, and Cu. These excitations have shown valuable applications but can also exhibit limiting physical effects associated with their materials composition, such as inherent losses (from the dielectric permittivity) and high oxidation (e.g., Ag, Al, Cu). A novel route to overcoming these limitations and achieving sustainable materials with improved optical properties is to interface plasmonic nanoparticles (NPs) with other dissimilar materials such as organic, semiconducting, and magnetic materials, and topological insulators. Here, I take a theoretical approach in understanding core systems of biomolecular- plasmonic, plasmonic-excitonic, and lastly, magneto-plasmonic. My systems are carefully built and modelled using numerical methods in order to identify the optical characteristics and the role of plasmons on their surroundings. Within this dissertation, I will discuss the role of plasmons on photothermal effects, local field enhancements in enhanced spectroscopies such as TERS and PL, as well as a possible pathway to optically control the magnetic properties of a system.