Tomchuk A. Spectral manifestations of near-field coupling in planar plasmonic nanostructures

The dissertation is devoted to: establishing the physical mechanisms of the hybridization collective plasmon mode in metal nanoparticles 2D-monolayer and propagating surface plasmon polariton mode of metal surface with consequent formation collective plasmon gap mode in planar plasmonic resonator-type structures "monolayer of metal nanoparticles (NP) / dielectric film / metal surface"; studying the effects of the characteristics such nanostructures on the excitation efficiency of these modes; researching of increasing the optical processes intensity in molecules inside plasmonic resonator nanostructures; analysis of the possibility of using these plasmon resonator nanostructures as a basis for the development of plasmonic devices, in which there is a need for a smoothly controlled variable optical response and highly sensitive sensors for fluorescent detection of biomolecules. The object of research is planar layered plasmonic nanostructures "2D layer of metal nanoparticles / dielectric film / metal surface". The subject of research is the influence of the effects of plasmonic near-field interaction on the spectral characteristics of planar plasmonic resonator nanostructures. In this research the following methods were used: spectroscopic (absorption, reflection, photoluminescence), microscopy (luminescence, atomic force, transmission and scanning electron), as well as numerical calculations, in particular by the FDTD method. The complex nature of the research with the help of well-developed and tested modern experimental techniques and theoretical calculations, the reproducibility of experimental results and the agreement of experimental data with the results of theoretical calculations gives grounds to consider the conducted research reliable. A detailed spectral and structural characterization of nanosystems made on the basis of Au, Ag, Al and Ni metals at room temperatures using modern experimental methods was carried out. Spectral characteristics of extinction in the system "monolayer of Au NPs / shellac interlayer / Al film" were analyzed. It is shown that when the thickness of the shellac layer decreases, the plasmon interaction increases, a strong red shift of the plasmon resonance peak and a nonlinear change in intensity with a maximum at a shellac film thickness of ~70 nm are observed. The considered planar nanostructure proves that the combination of "monolayer of metal NPs/ dielectric film/ metal film" allows to controllably change the spectral characteristics of the extinction peak by adjusting the size of the NPs, the interparticle distance, or the thickness of the dielectric layer. Optical spectroscopy methods have been used to determine the excitation conditions of the plasmonic gap mode in planar plasmonic nanostructures of different types. The excitation of the collective gap mode of the plasmonic nanoresonator "monolayer of Au NP / shellac layer / Al film" was revealed: at the shellac layer thickness < 30 nm, a new peak corresponds to the gap mode of the whole system appears in the extinction spectra due to the hybridization of the surface plasmonic mode of the NP layer and the delocalized plasmonic polariton mode of the metal film.