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Optical Properties of Metacrystals Based on Protein Nanocages |
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| Authors: | Niklas O. Junker Anja Lindenau Michael Rütten Marcel Lach Alexander Nedilko Dmitry N. Chigrin Gero von Plessen Tobias Beck |
| Affiliation: | 1. Institute of Physics (1A), RWTH Aachen University, Sommerfeldstraße 14, 52074 Aachen, Germany;2. Institute of Physical Chemistry, Department of Chemistry, Universität Hamburg, Grindelallee 117, 20146 Hamburg, Germany;3. Institute of Physics (1A), RWTH Aachen University, Sommerfeldstraße 14, 52074 Aachen, Germany DWI – Leibniz-Institut für Interaktive Materialien e.V., Forckenbeckstraße 50, 52074 Aachen, Germany |
| Abstract: | The optical properties of 3D metacrystals made of gold nanoparticles in protein nanocages are studied. These metacrystals have sizes of tens of micrometers and are of high structural and optical quality. Through microspectroscopy measurements and model calculations it is demonstrated that the metacrystals show plasmonic absorption in the green wavelength range and are largely transparent in the red and infrared ranges. By using empty nanocages as placeholders in the metacrystal lattice, it is possible to control how strongly the metamaterial absorbs. Measurements on a pyramidal metacrystal show that it deflects visible light. The deflection shows evidence for anomalous refraction at short wavelengths and normal refraction at long wavelengths. The refractive dispersion is ascribed to the optical dispersion relation of the plasmonic metamaterial. |
| Keywords: | anomalous refraction gold nanoparticles metacrystals microspectroscopy optical refraction protein nanocages |