Hostname: page-component-76fb5796d-x4r87 Total loading time: 0 Render date: 2024-04-25T07:00:14.633Z Has data issue: false hasContentIssue false
  • English
  • Français

Breakdown of the Dipole-Dipole Approximation at Short Distances and Hot Spot Formation between a Pair of Silver Nanocubes

Published online by Cambridge University Press:  20 May 2015

Nasrin Hooshmand ,
Justin A Bordley  and
Mostafa A El-Sayed
Nasrin Hooshmand
Affiliation:
Department of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
Justin A Bordley
Affiliation:
Department of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
Mostafa A El-Sayed*
Affiliation:
Department of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
*
*melsayed@gatech.edu
Get access

Abstract

Ag or Au nanocubes are known to be plasmonic nanoparticles with strong plasmonic fields concentrated around their corners1. When these nanoparticles aggregate the individual plasmonic oscillations of each particle begin to couple. The coupling between the two plasmonic nanoparticles is assumed to be dipolar in nature which results in an exponential red shift dependence of their localized surface plasmon resonance (LSPR) on the dimer separation2. Unfortunately, this exponential behavior is shown to fail as the separation distance between the two 42 nm nanocube dimer becomes 6nm or smaller3. Hooshmand et al4 have noted that these separation distances are marked by the formation of hot spots between the facets of the dimer.

This dipolar exponential behavior results from a treatment of the coupling between the two excited nanocubes as a coupling between two oscillating dipole moments2. As a result, the vectorial addition of all the oscillating electronic dipoles is assumed to interact with the nearest nanoparticle as a single oscillating electronic dipole. Herein we suggest that as the separation distance becomes increasingly small, the coupling between the individual oscillating dipoles on the different nanocubes becomes significant. Thus, the dipolar exponential behavior fails to accurately predict the near field coupling between two nanoparticles with small separation distances.

This leads to the realization that the interaction between the individual oscillating dipoles on the two nanocubes changes in a complicated manner as a function of separation distance. At 2nm, a good fraction of the oscillating dipoles are between the adjacent facets of the nanocubes as well as between the the corners. While at 3 nm less are in between the two facets of the nanocubes and a larger portion are localized at the corners. Thus, the coupling is not only dependent on the separation distance but also on what the separation does to the net interaction between the oscillating dipoles on each facet of the two coupled nanocubes. This results in the failure of the exponential behavior as the dipole moment on each nanocube is changing with distance in a complicated manner.

Keywords

nanostructureAgoptical properties
Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 1802: Symposium PP – Gold-Based Materials and Applications , 2015 , pp. 19 - 24
Copyright
Copyright © Materials Research Society 2015 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Kelly, K. L.; Coronado, E.; Zhao, L. L.; Schatz, G. C.: The Optical Properties of Metal Nanoparticles: The Influence of Size, Shape, and Dielectric Environment. The Journal of Physical Chemistry B 2002, 107, 668–677.CrossRefGoogle Scholar
Jain, P. K.; Huang, W.; El-Sayed, M. A.: On the Universal Scaling Behavior of the Distance Decay of Plasmon Coupling in Metal Nanoparticle Pairs: A Plasmon Ruler Equation. Nano Lett. 2007, 7, 2080–2088.CrossRefGoogle Scholar
Bordley, J. A.; Hooshmand, N.; El-Sayed, M. A.: The Coupling between Gold or Silver Nanocubes in their Homo-Dimers: A New Coupling Mechanism at Short Separation Distances. Nano Lett. 2015.CrossRefGoogle ScholarPubMed
Hooshmand, N.; Bordley, J. A.; El-Sayed, M. A.: Are Hot Spots between Two Plasmonic Nanocubes of Silver or Gold Formed between Adjacent Corners or Adjacent Facets? A DDA Examination. J. Phys. Chem. Lett. 2014, 5, 2229–2234.CrossRefGoogle ScholarPubMed
Lee, K. S.; El-Sayed, M. A.: Gold and silver nanoparticles in sensing and imaging: Sensitivity of plasmon response to size, shape, and metal composition. J. Phys. Chem. B 2006, 110, 19220–19225.CrossRefGoogle Scholar
Liz-Marzán, L. M.: Tailoring Surface Plasmons through the Morphology and Assembly of Metal Nanoparticles. Langmuir 2005, 22, 32–41.CrossRefGoogle Scholar
Sherry, L. J.; Chang, S.-H.; Schatz, G. C.; Duyne, Van, , R. P.; Wiley, B. J.; Xia, Y.: Localized Surface Plasmon Resonance Spectroscopy of Single Silver Nanocubes. Nano Lett. 2005, 5, 2034–2038.CrossRefGoogle ScholarPubMed
Link, S.; Wang, Z. L.; El-Sayed, M. A.: Alloy formation of gold-silver nanoparticles and the dependence of the plasmon absorption on their composition. J. Phys. Chem. B 1999, 103, 3529–3533.CrossRefGoogle Scholar
Jensen, T. R.; Malinsky, M. D.; Haynes, C. L.; Van Duyne, R. P.: Nanosphere Lithography: Tunable Localized Surface Plasmon Resonance Spectra of Silver Nanoparticles. The Journal of Physical Chemistry B 2000, 104, 10549–10556.CrossRefGoogle Scholar
Haynes, C. L.; Van Duyne, R. P.: Nanosphere Lithography: A Versatile Nanofabrication Tool for Studies of Size-Dependent Nanoparticle Optics. The Journal of Physical Chemistry B 2001, 105, 5599–5611.CrossRefGoogle Scholar
Murray, W. A.; Auguié, B.; Barnes, W. L.: Sensitivity of Localized Surface Plasmon Resonances to Bulk and Local Changes in the Optical Environment. The Journal of Physical Chemistry C 2009, 113, 5120–5125.CrossRefGoogle Scholar
Maier, S. A.: Plasmonics: Metal Nanostructures for Subwavelength Photonic Devices. Selected Topics in Quantum Electronics, IEEE Journal of 2006, 12, 1214–1220.CrossRefGoogle Scholar
Haes, A. J.; Chang, L.; Klein, W. L.; Van Duyne, R. P.: Detection of a Biomarker for Alzheimer's Disease from Synthetic and Clinical Samples Using a Nanoscale Optical Biosensor. Journal of the American Chemical Society 2005, 127, 2264–2271.CrossRefGoogle ScholarPubMed
Zhao, J.; Zhang, X.; Yonzon, C. R.; Haes, A. J.; Van Duyne, R. P.: Localized surface plasmon resonance biosensors. Nanomedicine 2006, 1, 219–228.CrossRefGoogle ScholarPubMed
Reinhard, B. M.; Siu, M.; Agarwal, H.; Alivisatos, A. P.; Liphardt, J.: Calibration of Dynamic Molecular Rulers Based on Plasmon Coupling between Gold Nanoparticles. Nano Lett. 2005, 5, 2246–2252.CrossRefGoogle ScholarPubMed
Xue, C.; Li, Z.; Mirkin, C. A.: Large-Scale Assembly of Single-Crystal Silver Nanoprism Monolayers. Small 2005, 1, 513–516.CrossRefGoogle ScholarPubMed
Funston, A. M.; Novo, C.; Davis, T. J.; Mulvaney, P.: Plasmon Coupling of Gold Nanorods at Short Distances and in Different Geometries. Nano Lett. 2009, 9, 1651–1658.CrossRefGoogle ScholarPubMed
Jain, P. K.; El-Sayed, M. A.: Surface plasmon coupling and its universal size scaling in metal nanostructures of complex geometry: Elongated particle pairs and nanosphere trimers. J. Phys. Chem. C 2008, 112, 4954–4960.CrossRefGoogle Scholar
Tabor, C. E.; Murali, R.; Mahmoud, M. A.; El-Sayed, M. A.: On the Use of Plasmonic Nanoparticle Pairs As a Plasmon Ruler: The Dependence of the Near-Field Dipole Plasmon Coupling on Nanoparticle Size and Shape. J. Phys. Chem. A 2009, 113, 1946–1953.CrossRefGoogle ScholarPubMed
Su, K. H.; Wei, Q. H.; Zhang, X.; Mock, J. J.; Smith, D. R.; Schultz, S.: Interparticle Coupling Effects on Plasmon Resonances of Nanogold Particles. Nano Lett. 2003, 3, 1087–1090.CrossRefGoogle Scholar
Gunnarsson, L.; Rindzevicius, T.; Prikulis, J.; Kasemo, B.; Käll, M.; Zou, S.; Schatz, G. C.: Confined Plasmons in Nanofabricated Single Silver Particle Pairs: Experimental Observations of Strong Interparticle Interactions. The Journal of Physical Chemistry B 2004, 109, 1079–1087.CrossRefGoogle Scholar
Draine, B. T.; Flatau, P. J.: Discrete-dipole approximation for scattering calculations. J. Opt. Soc. Am. A 1994, 11, 1491–1499.CrossRefGoogle Scholar