Volume 119, Number 2, July 2017
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||05 October 2017|
Optical properties of anisotropic 3D nanoparticles arrays(a)
Instituto de Física, Universidad Nacional Autónoma de México - Apdo. Postal 20-364, México D.F. 01000, México
Received: 26 July 2017
Accepted: 18 September 2017
The optical properties of 3D periodic arrays of spheroidal Au nanoparticles are calculated using a Bruggeman effective medium approximation. The optical response of the supra-crystal depends on the volume fraction of the nanoparticles and their aspect or size ratio (major/minor axis). All the nanoparticles have the same orientation, and this defines an anisotropic dielectric function of the crystal. As a function of the filling fraction, while keeping the size ratio fixed, the maximum in the extinction spectra along the major and minor axes does not show a significant change. However, for a fixed filling fraction, varying the aspect ratio of the particles induces a shift of several hundred of nanometers in the maximum of the extinction spectra along the major axis and almost no changes along the minor axis. Depending on the aspect ratio and the filling fraction, we show that the supra-crystal has three regimes with different values of an effective plasma frequency.
PACS: 78.67.Bf – Nanocrystals, nanoparticles, and nanoclusters / 73.20.Mf – Collective excitations (including excitons, polarons, plasmons and other charge-density excitations) / 64.75.Yz – Self-assembly
© EPLA, 2017
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