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Electromagnetic enhancement of ordered silver nanorod arrays evaluated by discrete dipole approximation

The enhancement factor (EF) of surface-enhanced Raman scattering (SERS) from two-dimensional (2D) hexagonal silver nanorod (AgNR) arrays were investigated in terms of electromagnetic (EM) mechanism by using the discrete dipole approximation (DDA) method. The dependence of EF on several parameters, i...

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Autores principales: Wei, Guoke, Wang, Jinliang, Chen, Yu
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Beilstein-Institut 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4362013/
https://www.ncbi.nlm.nih.gov/pubmed/25821708
http://dx.doi.org/10.3762/bjnano.6.69
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author Wei, Guoke
Wang, Jinliang
Chen, Yu
author_facet Wei, Guoke
Wang, Jinliang
Chen, Yu
author_sort Wei, Guoke
collection PubMed
description The enhancement factor (EF) of surface-enhanced Raman scattering (SERS) from two-dimensional (2D) hexagonal silver nanorod (AgNR) arrays were investigated in terms of electromagnetic (EM) mechanism by using the discrete dipole approximation (DDA) method. The dependence of EF on several parameters, i.e., structure, length, excitation wavelength, incident angle and polarization, and gap size has been investigated. “Hotspots” were found distributed in the gaps between adjacent nanorods. Simulations of AgNR arrays of different lengths revealed that increasing the rod length from 374 to 937 nm (aspect ratio from 2.0 to 5.0) generated more “hotspots” but not necessarily increased EF under both 514 and 532 nm excitation. A narrow lateral gap (in the incident plane) was found to result in strong EF, while the dependence of EF on the diagonal gap (out of the incident plane) showed an oscillating behavior. The EF of the array was highly dependent on the angle and polarization of the incident light. The structure of AgNR and the excitation wavelength were also found to affect the EF. The EF of random arrays was stronger than that of an ordered one with the same average gap of 21 nm, which could be explained by the exponential dependence of EF on the lateral gap size. Our results also suggested that absorption rather than extinction or scattering could be a good indicator of EM enhancement. It is expected that the understanding of the dependence of local field enhancement on the structure of the nanoarrays and incident excitations will shine light on the optimal design of efficient SERS substrates and improved performance.
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spelling pubmed-43620132015-03-27 Electromagnetic enhancement of ordered silver nanorod arrays evaluated by discrete dipole approximation Wei, Guoke Wang, Jinliang Chen, Yu Beilstein J Nanotechnol Full Research Paper The enhancement factor (EF) of surface-enhanced Raman scattering (SERS) from two-dimensional (2D) hexagonal silver nanorod (AgNR) arrays were investigated in terms of electromagnetic (EM) mechanism by using the discrete dipole approximation (DDA) method. The dependence of EF on several parameters, i.e., structure, length, excitation wavelength, incident angle and polarization, and gap size has been investigated. “Hotspots” were found distributed in the gaps between adjacent nanorods. Simulations of AgNR arrays of different lengths revealed that increasing the rod length from 374 to 937 nm (aspect ratio from 2.0 to 5.0) generated more “hotspots” but not necessarily increased EF under both 514 and 532 nm excitation. A narrow lateral gap (in the incident plane) was found to result in strong EF, while the dependence of EF on the diagonal gap (out of the incident plane) showed an oscillating behavior. The EF of the array was highly dependent on the angle and polarization of the incident light. The structure of AgNR and the excitation wavelength were also found to affect the EF. The EF of random arrays was stronger than that of an ordered one with the same average gap of 21 nm, which could be explained by the exponential dependence of EF on the lateral gap size. Our results also suggested that absorption rather than extinction or scattering could be a good indicator of EM enhancement. It is expected that the understanding of the dependence of local field enhancement on the structure of the nanoarrays and incident excitations will shine light on the optimal design of efficient SERS substrates and improved performance. Beilstein-Institut 2015-03-09 /pmc/articles/PMC4362013/ /pubmed/25821708 http://dx.doi.org/10.3762/bjnano.6.69 Text en Copyright © 2015, Wei et al. https://creativecommons.org/licenses/by/2.0https://www.beilstein-journals.org/bjnano/termsThis is an Open Access article under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The license is subject to the Beilstein Journal of Nanotechnology terms and conditions: (https://www.beilstein-journals.org/bjnano/terms)
spellingShingle Full Research Paper
Wei, Guoke
Wang, Jinliang
Chen, Yu
Electromagnetic enhancement of ordered silver nanorod arrays evaluated by discrete dipole approximation
title Electromagnetic enhancement of ordered silver nanorod arrays evaluated by discrete dipole approximation
title_full Electromagnetic enhancement of ordered silver nanorod arrays evaluated by discrete dipole approximation
title_fullStr Electromagnetic enhancement of ordered silver nanorod arrays evaluated by discrete dipole approximation
title_full_unstemmed Electromagnetic enhancement of ordered silver nanorod arrays evaluated by discrete dipole approximation
title_short Electromagnetic enhancement of ordered silver nanorod arrays evaluated by discrete dipole approximation
title_sort electromagnetic enhancement of ordered silver nanorod arrays evaluated by discrete dipole approximation
topic Full Research Paper
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4362013/
https://www.ncbi.nlm.nih.gov/pubmed/25821708
http://dx.doi.org/10.3762/bjnano.6.69
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