The Maxwell-Garnett model used to calculate the transmission spectra of composite films with copper and gold nanoparticles

Muratov D.A., Nikolaev N.E., Chekhova T.K.

Institute of Physical Research and Technology (IFIT) Patrice Lumumba Peoples' Friendship University of Russia (RUDN) Miklukho-Maklaya str., Moscow, 117198, Russia, 6, +7(495)9550825,

The study of the optical properties of composite media containing nanoparticles is one of the perspective areas of physics. These media acquire properties unattainable for conventional materials. The use of these properties is possible for creating sensors, films and devices for recording and transmitting optical information. When metal nanoparticles are included into a homogeneous medium, an optical nanostructure with properties different from those of the original medium is created. The choice of metal as the substance of nanoparticles is due to the fact that the resulting systems have absorbing properties, which affects their photocatalytic properties and is important in the creation of solar cells. The optical properties of films can be controlled and, thereby, their characteristics can be improved. One of the ways to control the properties of optical media is to change the shape of the particles used.

In this paper, a study of composite media with gold and copper nanoparticles was carried out. To analyze the optical properties of such nanocomposites, the Maxwell Garnett model of an effective medium with a variable depolarization factor was used [1]. The paper presents expressions for the reflection, transmission and absorption coefficients of a composite medium containing nanoparticles shaped like ellipsoids of rotation with the ratios of the main axes 1/2, 1, 2. The volume concentration of particles in the film was 1%.

The dispersion dependences of the reflection and transmission coefficients of films [2] with gold and copper nanoparticles of ellipsoidal shape are calculated depending on different angles of incidence of radiation and the ratio of the main axes of the ellipsoid of rotation.

The dependences of the reflection and transmission coefficients of composite media with gold and copper nanoparticles of various shapes obtained in the work show that the absorption region almost does not change when gold particles are replaced with copper ones.

It was found that the use of particles of a more elongated shape leads to a shift in characteristics to the long-wavelength region and an increase in the resonant absorption band.

Calculations have shown that for composite media with elongated nanoparticles, an increase in the angle of incidence of an electromagnetic wave leads to a shift in the absorption region and an approximation of its shape and width to the corresponding parameters of a similar region on the graph for spherical particles.


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