The dissertation is devoted to an important scientific and technical problem - the theoretical investigation of the optical properties of metallic and hybrid nanostructures (core-shell nanostructures) aimed at optimizing their parameters for sensor applications based on localized surface plasmon resonance (LSPR). The relevance of the work is due to the fact the growing demand for highly sensitive optical sensors for biomedical diagnostics, environmental monitoring, analytical chemistry, and related fields. Plasmonic nanostructures represent a promising platform for such applications due to
their high sensitivity to environmental changes and their ability to enhance the electromagnetic field.
The introduction substantiates the relevance of the research, outlines its objectives and scientific and technical tasks, demonstrates its connection with ongoing scientific programs, highlights the novelty and practical significance of the results, and defines the author's personal contribution. Information regarding the approbation of the results is also presented.
The aim of the work is to establish the regularities governing the influence of geometric and material parameters of metallic and hybrid nanostructures on the characteristics of localized surface plasmon resonance in order to optimize their
sensing properties.
The object of the research is optical phenomena in metallic nanoparticles, metalorganic core-shell nanostructures, and periodic plasmonic structures. The subject of the research is the spectral characteristics of plasmon resonance and their dependence on geometric and material parameters of nanostructures as well as on the surrounding environment.
The object of the research is optical phenomena in metallic nanoparticles, metalorganic core-shell nanostructures, and periodic plasmonic structures. The subject of the research is the spectral characteristics of plasmon resonance and their dependence on geometric and material parameters of nanostructures as well as on the surrounding environment.
The second chapter presents the theoretical foundations and practical implementation of a numerical simulation algorithm for the optical properties of plasmonic metal-polymer nanostructures. The influence of the refractive index of the
surrounding medium on the spectral position and intensity of the localized surface plasmon resonance of metal-polymer nanoshells is investigated. The regularities of plasmon peak shifts for various polymer matrices are established, and specific features of multimode behavior in individual systems are revealed. A systematic parametric
analysis of the influence of geometric parameters — namely the metal core radius and polymer shell thickness — on the optical response of hybrid nanostructures is carried out. Quantitative dependences of the spectral position and amplitude of the plasmon resonance on the size ratio of the core-shell system components are established for various polymer materials.
The third chapter describes the algorithm for numerical simulation of the optical properties of plasmonic ellipsoidal silver nanoparticles. The expediency of transitioning from spherical to ellipsoidal nanoparticle geometry as a tool for
expanding the spectral range and enhancing the anisotropy of the plasmonic response is substantiated. A comparative analysis of plasmon absorption by spherical nanoparticles of silver, gold, and copper is performed. The influence of nanoparticle shape on optical properties is investigated through simulation of plasmon absorption by ellipsoidal silver nanoparticles with various aspect ratios. The dependences of
spectral splitting of longitudinal and transverse plasmon modes on the degree of nanoparticle elongation are established. An algorithm for calculating the interaction of silver nanoparticles with a substrate is presented, accounting for the change in the local dielectric environment of the nanoparticle due to its contact with the substrate and the corresponding modification of plasmon resonance excitation conditions. Simulations
of the influence of substrate material on the extinction cross-section spectra of silver nanoparticles are carried out. Quantitative regularities of plasmon peak shift and transformation depending on the dielectric properties of the substrate are established, which is of importance for the practical application of plasmonic nanostructures in sensing devices.
Keywords: surface, nanostructures, thin films, sensors, optical identification, modeling, hybrid structures, graphene, extinction coefficient, absorption, scattering, refractive index, nanoparticles, silver, gold, resonance, plasmon resonance, waveguide resonance, diffraction gratings.
