Irina A. Boginskaya

Structural and optical properties of single and bilayer silver and gold films

An experimental study of structural and optical properties of silver and gold thin films, as well as bilayer films based on these metals, has been carried out. To study properties of nanofilms, reflection spectra upon excitation of surface plasmons in the Kretschmann geometry and spectra of ellipsometric parameters have been investigated. The reflection spectra were analyzed using a theoretical model for determining (effective) dielectric constants of the films. The calculated dielectric constants of the films differ from data obtained by ellipsometry. The features in determining dielectric constants by different methods and characteristics of manufactured films in relation to the influence of the substrate are discussed.

Light localization and SERS in tip-shaped silicon metasurface

Optical properties of two dimensional periodic system of the silicon micro-cones are investigated. The metasurface, composed of the silicon tips, shows enhancement of the local optical field. Finite element computer simulations as well as real experiment reveal anomalous optical response of the dielectric metasurface due to excitation of the dielectric resonances. Various electromagnetic resonances are considered in the dielectric cone. The metal-dielectric resonances, which are excited between metal nanoparticles and dielectric cones, are also considered. The resonance local electric field can be much larger than the field in the usual surface plasmon resonances. To investigate local electric field the signal molecules are deposited on the metal nanoparticles. We demonstrate enhancement of the electromagnetic field and Raman signal from the complex of DTNB acid molecules and gold nanoparticles, which are distributed over the metasurface. The metasurfaces composed from the dielectric resonators can have quasi-continuous spectrum and serve as an efficient SERS substrates.

Enhancement of SERS signal using new material based on cerium dioxide facet dielectric films

In this paper, we investigate the potential of facet structures of cerium dioxide for the purpose of increasing the intensity of the surface enhancement Raman scattering (SERS) signal. During the studies, a new metamaterial is developed. The metamaterial is based on facet cerium dioxide films and plasmonic nanoparticles that are immobilized on its surface. The new metamaterial provides an additional SERS signal amplification factor of more than 200. Thus developed material offers the prospect of increasing the sensitivity and selectivity of biochemical and immunological analysis.

Giant field fluctuations in dielectric metamaterial and Raman sensor

New dielectric metamaterial based on the Bragg filter comprising ten dielectric bilayers was investigated. Each bilayer is the thin films of silicone dioxide (SiO2) and another film of zirconium dioxide (ZrO2). The surface of the multilayer film is profiled. It has a form of periodic system of rectangles separated by the open gaps. We use the computer simulation as well as analytical solution to find the reflectance of the multilayer as a function of the wavelength and electromagnetic (em) field distribution. The multilayer system reveals the enhancement of em fields at the surface. The considered Bragg filter was modified by Raman-active structure made of gold nanoparticles with chemically attached 3,3-thio-bis(6- nitrobenzoic acid) - (TNB). The high Surface Enhanced Raman Scattering (SERS) signal was detected.

Metal-dielectric resonances in tip silicon metasurface and SERS based nanosensors

Optical properties of two-dimensional periodic systems of the dielectric micro bars and micro cones are investigated. Computer simulations as well as real experiment reveal anomalous optical response of the dielectric metasurface due to excitation of the dielectric and metal-dielectric resonances, which are excited in-between metal nanoparticles and dielectric cones and bars. In the metal-dielectric resonance local electric field can be orders on magnitude larger than the field in the plasmon resonance only. To investigate local electric field the signal molecules were deposited on the metal nanoparticles. We demonstrate the enhancement of the electro- magnetic field by detecting the Raman signal from the of organic acid molecules deposited on the investigated metasurface.

Poly(p-xylylene) Silver Nanocomposites: Optical, Radiative, and Structural Properties

We perform a detailed investigation of coatings made of poly(p-xylylene) nanocomposites with embedded silver nanoparticles of sizes up to 12 nm and concentration up to 10.5 vol. %. We study their microstructure, mechanical, optical, and radiative characteristics. We reveal certain correlations between structural peculiarities and optical, as well as radiative properties. These correlations are due to fluctuations in distribution of nanoparticles in a polymer matrix and also due to the peculiarities of nanoparticles size distribution. We calculated optical dispersion coefficients for nanocomposites with different silver content. It was shown the refractive index ( n) and extinction coefficient (k) is strongly dependent on the silver content and change within the 1.4–2.4 for n and 0–0.6 for the k. It is argued that poly(p-xylylene)silver nanocomposites can be used to construct multilayer coatings with required optical constant and conformal to any complex morphology.

Sensors based on dielectric metamaterials

The possibility of amplification of local electric fields on the surface of thin dielectric films of complex structure is considered. Amplification of the optical field enables an increase in the intensity of the Raman scattering signal and provides broad opportunities for the development of novel biochemical sensors.

Application of method of light scattering indicatrix analysis for study of microstructure of poly( p -xylylene)-silver nanocomposites

A comprehensive study of the microstructure of poly(p-xylylene)-silver (PPX-Ag) nanocomposites is carried out using the method of light scattering indicatrix analysis. A stand for measurements of light scattering indicatrix and integral light scattering is created. Theoretical calculations of the PPX-Ag scattering indicatrices using Mie theory are performed taking into account the features of the microstructure of the nanocomposite. Good agreement of the experimental and theoretical studies of the PPX-Ag scattering indicatrices is obtained.

Using the metal-polymer nanocomposite polyparaxylylene-Ag as a medium with assigned optical characteristics

This article is devoted to a study of the optical properties of the new material polyparaxylylene-Ag, which is of interest as a promising material for creating optics elements.