Specific electric polarizability of copper nanoparticles in the optical range of the spectrum

Oleksandr Viktorovych Machulianskyi

doi:10.20535/2523-4455.2018.23.2.130732

Abstract

Work is devoted to a research of dimensional changes in optical properties of nanosized copper particles with sizes less than 10 nm in statistically inhomogeneous systems. Experimental spectral and dimensional dependences of the complex specific electric polarizability of nanosized copper particles with experimental-analytical method are determined in the optical spectral range from 0.2 to 1.1 μm. The values of the complex specific electric polarizability were determined by analytical solution of Rosenberg’s spectrophotometric equations with the use of experimental results of spectrophotometric measurements of transmission and reflection coefficients of copper islet films and the results of electron microscopic studies of their morphological microstructure, taking into account the statistical analysis of the particle size distribution. Nanosized copper particles with a statistically inhomogeneous structure in the system of islet films on quartz substrates were obtained by vacuum-magnetron sputtering. An analysis of function of copper nanoparticles distribution in size in a system with a statistically inhomogeneous structure was carried out using the Pearson’s consensus criterion.To find out the features of optical absorption of nanosized copper particles, their experimental spectral and dimensional dependences of the complex specific electric polarizability are compared with the corresponding characteristics for model particles with properties characteristic for macroscopic volumes of copper. It was found that the optical properties of nanosized copper particles differ from optical properties of copper in a macroscopic volume. An increase in the absolute values of the components of the complex specific electric polarizability of spherical nanosized copper particles with decreasing their diameter within the range from 8 nm to 3.2 nm for wavelengths of 0.2 - 1.1 μm is established.The spectral dependences of optical parameters of nanosized copper particles according to well-known theories of classical and quantum dimensional effects are calculated. In order to study the nature of dimensional dependences of optical parameters of copper nanoparticles, a comparative analysis of calculated and experimental spectral and dimensional dependences of their optical parameters was carried out. It is shown that the experimental dimensional changes in the complex specific electric polarizability of copper particles in the investigated range of sizes not be due to the classical or quantum dimensional effect in the dipole approximation.Ref. 36, fig. 3.

Highlights

Nanosized metal particles and nanostructured metaldielectric systems on their basis have a number of nonlinear optical effects
It is shown that taking into account the analysis of the particle size distribution in the experimental-analytical method makes it possible to apply this approach to nanostructured systems with a statistically inhomogeneous structure and reliably estimate their optical parameters
The experimental-analytical method makes it possible to determine the optical parameters of nanoscale particles depending on their morphological microstructure in the system

Summary

Introduction

Nanosized metal particles and nanostructured metaldielectric systems on their basis have a number of nonlinear optical effects. It determines a widespread practical application of these structures in optoelectronics [1], information security and transmission systems [2], photoelectric and photothermal energy converters for energysaving technologies [3, 4]. The example of nanostructured metal-dielectric system future usage is the optical waveguides for interconnections at the upper levels of integrated circuits [5] In this case, the electro-optical receivers and emitters converting electric signals in the light are formed it the metal-dielectric layers of dielectric. These integrated optoelectronic devices can accelerate the information transmission by two orders and significantly decrease the energy consumption [6].

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