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Broadband optical absorption caused by the plasmonic response of coalesced au nanoparticles embedded in a TiO2 matrix

Broadband optical absorption caused by the plasmonic response of coalesced au nanoparticles embedded in a TiO2 matrix
Broadband optical absorption caused by the plasmonic response of coalesced au nanoparticles embedded in a TiO2 matrix
The effect of Au nanoparticles’ (NPs) concentration, size, and spatial distribution within a TiO2 dielectric matrix on the localized surface plasmon resonance (LSPR) band characteristics was experimentally and theoretically studied. The results of the analysis of the Au NPs’ size distributions allowed us to conclude that isolated NPs grow only up to 5 to 6 nm in size, even for the highest annealing temperature used. However, for higher volume fractions of Au, the coalescence of closely located NPs yields elongated clusters that are much larger in size and cause a considerable broadening of the LSPR band. This effect was confirmed by Monte Carlo modeling results. Coupled dipole equations were solved to find the electromagnetic modes of a supercell, where isolated and coalesced NPs were distributed, from which an effective dielectric function of the nanocomposite material was calculated and used to evaluate the optical transmittance and reflectance spectra. The modeling results suggested that the observed LSPR band broadening is due to a wider spectral distribution of plasmonic modes, caused by the presence of coalesced NPs (in addition to the usual damping effect). This is particularly important for detection applications via surface-enhanced Raman spectroscopy (SERS), where it is desirable to have a spectrally broad LSPR band in order to favor the fulfillment of the conditions of resonance matching, to electronic transitions in detected species.
1932-7447
16931-16945
Borges, J.
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Pereira, R
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Rodrigues, M.S.
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Kubart, T.
dd6b00f9-b497-47ac-9cfe-20aac030366d
Kumar, S.
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Leifer, K.
c85ff2f6-ded0-440c-9f95-61e2526f3573
Cavaleiro, A.
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Polcar, T.
c669b663-3ba9-4e7b-9f97-8ef5655ac6d2
Vasilevskiy, M. I.
dcf70478-adb2-4cf2-b769-8d61babd8ba7
Faz, V.
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Borges, J.
c8e5c89d-68cf-454e-a7c3-4f4629f32120
Pereira, R
31c8f2ab-af73-4ea0-b80c-e1fdd6e9e7a6
Rodrigues, M.S.
8ee697c5-af21-45e7-b905-a1f76b4c0b47
Kubart, T.
dd6b00f9-b497-47ac-9cfe-20aac030366d
Kumar, S.
695e30ec-08ac-4ad7-9f6b-b18dc52bcd0b
Leifer, K.
c85ff2f6-ded0-440c-9f95-61e2526f3573
Cavaleiro, A.
114e42eb-7255-47ef-834d-0546d56d3171
Polcar, T.
c669b663-3ba9-4e7b-9f97-8ef5655ac6d2
Vasilevskiy, M. I.
dcf70478-adb2-4cf2-b769-8d61babd8ba7
Faz, V.
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Borges, J., Pereira, R, Rodrigues, M.S., Kubart, T., Kumar, S., Leifer, K., Cavaleiro, A., Polcar, T., Vasilevskiy, M. I. and Faz, V. (2016) Broadband optical absorption caused by the plasmonic response of coalesced au nanoparticles embedded in a TiO2 matrix. The Journal of Physical Chemistry C, 16931-16945. (doi:10.1021/acs.jpcc.6b03684).

Record type: Article

Abstract

The effect of Au nanoparticles’ (NPs) concentration, size, and spatial distribution within a TiO2 dielectric matrix on the localized surface plasmon resonance (LSPR) band characteristics was experimentally and theoretically studied. The results of the analysis of the Au NPs’ size distributions allowed us to conclude that isolated NPs grow only up to 5 to 6 nm in size, even for the highest annealing temperature used. However, for higher volume fractions of Au, the coalescence of closely located NPs yields elongated clusters that are much larger in size and cause a considerable broadening of the LSPR band. This effect was confirmed by Monte Carlo modeling results. Coupled dipole equations were solved to find the electromagnetic modes of a supercell, where isolated and coalesced NPs were distributed, from which an effective dielectric function of the nanocomposite material was calculated and used to evaluate the optical transmittance and reflectance spectra. The modeling results suggested that the observed LSPR band broadening is due to a wider spectral distribution of plasmonic modes, caused by the presence of coalesced NPs (in addition to the usual damping effect). This is particularly important for detection applications via surface-enhanced Raman spectroscopy (SERS), where it is desirable to have a spectrally broad LSPR band in order to favor the fulfillment of the conditions of resonance matching, to electronic transitions in detected species.

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JBorges_Manuscript_JPCc - Accepted Manuscript
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Accepted/In Press date: 11 April 2016
e-pub ahead of print date: 1 July 2016
Published date: 4 August 2016
Organisations: nCATS Group

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Local EPrints ID: 407700
URI: https://eprints.soton.ac.uk/id/eprint/407700
ISSN: 1932-7447
PURE UUID: 9fcf8c42-8e1c-4fb7-8068-df7256a3ba9a
ORCID for T. Polcar: ORCID iD orcid.org/0000-0002-0863-6287

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Date deposited: 22 Apr 2017 01:09
Last modified: 15 Aug 2019 04:58

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Contributors

Author: J. Borges
Author: R Pereira
Author: M.S. Rodrigues
Author: T. Kubart
Author: S. Kumar
Author: K. Leifer
Author: A. Cavaleiro
Author: T. Polcar ORCID iD
Author: M. I. Vasilevskiy
Author: V. Faz

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