Anisotropy Effects on the Plasmonic Response of Nanoparticle Dimers

Journal Of Physical Chemistry Letters 6, 1891 - 1898 (2015)

Anisotropy Effects on the Plasmonic Response of Nanoparticle Dimers

Alejandro Varas, Pablo García-González, F. J. García-Vidal, Angel Rubio

We present an ab-initio study of the anisotropy and atomic relaxation effects on the optical properties of nanoparticle dimers. Special emphasis is put on the hybridization process of localized surface plasmons, the plasmon-mediated photoinduced currents, and the electric-field enhancement in the dimer junction. We show that there is a critical range of separations between the clusters (from 0.1 to 0.5 nm) in which the detailed atomic structure in the junction and the relative orientation of the nanoparticles have to be considered to obtain quantitative predictions for realistic nanoplasmonic devices. It is worth noticing that this regime is characterized by the emergence of electron tunneling as a response to the driven electromagnetic field. The orientation of the particles not only modifies the attainable electric field enhancement but can lead to qualitative changes in the optical absorption spectrum of the system.

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We thankfully acknowledge the financial support by the European Research Council (ERC- 2010-AdG Proposal No. 267374 and ERC-2011-AdG Proposal No. 290891), the Spanish Government (grants MAT2011-28581-C02-01, FIS2013-46159-C3-1-P, MAT2014-53432-C5-5-R), and the Basque Country Government (Grupos Consolidados IT-578-13). We also appreciate the technical support by Joseba Alberdi-Rodríguez and fruitful discussions with Prof. Javier Aizpurua, Prof. Andrei G. Borisov, Prof. Juan Carlos Cuevas, Dr. Johannes Feist, Dr. Antonio Fernández-Domínguez, and Dr. Pu Zhang.

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