Plasmonic Self-Assembled Colloidal Magnetic Resonators

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[Under construction - Nick Schade (fall 2009)]

Plasmonic self-assembled colloidal magnetic resonators have been demonstrated in this study. These are clusters of metallic colloidal nanoparticles that support magnetic dipole resonances at near-infrared frequencies. Each cluster, or trimer, consists of three gold nanospheres coated with polymer that have undergone self-assembly from solution. The resulting structures permit separation gaps between the particles of about two nanometers, which surpasses the resolution obtainable through traditional approaches such as lithography. This result demonstrates that self-assembly offers a promising route to low cost and complex three dimensional metamaterials.

General Information

Keywords: colloid, self-assembly, plasmon

Authors: Jonathan A. Fan, Chih Hui Wu, Jiming Bao, Rizia Bardhan, Naomi J. Halas, Vinny Manoharan, Gennady Shvets, and Federico Capasso.

Date: 2009 (in review).

School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA.

Department of Physics, University of Texas at Austin, 1 University Station C1600, Austin, TX 78712, USA.

Department of Electrical and Computer Engineering, University of Houston, N308 Engineering Building 1, Houston, TX 77204, USA.

Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, MS-366, Houston, TX 77005, USA.

Summary

Researchers are interested in colloidal metallic nanostructures because they can support surface plasmons, or oscillations of free electrons in the metal that couple with the electromagnetic field. The plasmonic properties of nanostructures depend strongly on their geometric and material properties. Precision at the nanometer scale is necessary to tune the resonant frequencies supported by these structures and self-assembly of the colloidal particles is one way that this could be achieved. Here the authors have assembled trimers of three dielectric-coated gold nanoparticles with controllable gap separations and measured their electromagnetic properties with correlated scattering spectroscopy.


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