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The Coupling between Gold or Silver Nanocubes in Their Homo-Dimers: A New Coupling Mechanism at Short Separation Distances.

Authors
  • Bordley, Justin A1
  • Hooshmand, Nasrin1
  • El-Sayed, Mostafa A1, 2
  • 1 †Department of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States. , (Georgia)
  • 2 ‡King Abdulaziz University, Department of Chemistry, Jeddah 22254, Saudi Arabia. , (Saudi Arabia)
Type
Published Article
Journal
Nano Letters
Publisher
American Chemical Society
Publication Date
May 13, 2015
Volume
15
Issue
5
Pages
3391–3397
Identifiers
DOI: 10.1021/acs.nanolett.5b00734
PMID: 25844929
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

Using the DDA method, we investigated the near-field coupling between two excited Au or Ag 42 nm nanocubes in a face-to-face dimer configuration at small separation distances where the exponential coupling behavior distinctly changes. This could be due to the failure of the dipole approximation at short distances or a change in the electromagnetic field distribution between the adjacent monomers. A detailed calculation of the plasmonic field distribution strongly suggests that the latter mechanism is responsible for the failure of the expected exponential coupling behavior at small separation distances. The results suggest that the observed optical properties of the pair of Au or Ag nanocubes separated by distances larger than 6 nm, result from the electromagnetic coupling between the oscillating dipoles at the corners of the adjacent facets of the nanocubes. At separations smaller than 6 nm, the distribution of the plasmonic dipoles along both the facets and the corners of the adjacent monomers control the plasmonic spectra and the distance dependent optical properties of the dimer.

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