Nanostructured surfaces

Configurational resonances for the silicon surface covered with  metallic nanoparticles 
V.Z. Lozovski1, Z.Ya. Zhuchenko2, G.G. Tarasov2, T.A. Vasyliev1
1Taras Shevchenko National University of Kyiv. Volodymyrska, 60, Kyiv-01033, Ukraine
2 Institute of Semiconductor Physics, National Acad. of Sci. of Ukraine, Prospect Nauki 45, Kyiv-03028, Ukraine.

E-mail: taras.a.vasiliev@gmail.com
The geometrical resonances are well known to strongly affect near-field imaging of surface[1]. Theoretical analysis of the interaction between the dielectric probe and the surface predicts that there are regions close to the surface where an enhanced field can be induced by the probe, while, when the tip-surface distance decreases to zero, the self-consistent field tends to zero. As a result the resonance interactions between the probe tip and the surface exist. These resonances are described as configurational ones, while, for any given dipole polarizabilities, the system can be adjusted to resonance by varying the distances between the dipoles. 
In present study a silicon surface covered with metallic spheroidal nanoparticles is considered. The characteristic linear sizes of nanoparticles are nearly 10-20 nm. The material parameters of golden and copper nanoparticles were taken from Ref. [2]. The theoretical approach used for calculation of light absorption by coverings from metallic spheroidal nanoparticles onto silicon surface is based on the concept of effective susceptibility introduced by Lozovski [3]. The absorption spectra were calculated for coverings with nanoparticles having different shapes and their surface densities at different angles of external light incidence. Obtained results predict strong configurational resonances in the spectral range where the absorption was maximum, i.e. resonant enhancing of absorption by coverings of nanoparticles of certain shape and density.

1.O. Keller, M. Xiao, and S.  Bozhevolnyi,” Configurational resonances in optical near-field microscopy: a rigorous point-dipole approach”, Surf. Sci. 280, 217 (1993).
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3. V.Z.Lozovski The effective susceptibility concept in the electrodynamics of nano-systems // J. Computation. and Theor. Nanosci. – 2010. - 7 (10). - P. 2077