Broadband Optical Absorption Caused by the Plasmonic Response of Coalesced Au Nanoparticles Embedded in a TiO2 Matrix | Zendy

Joel Borges | Zendy; Rui M. S. Pereira | Zendy; Marco S. Rodrigues | Zendy; Tomáš Kubart | Zendy; S. Suresh Kumar | Zendy; Klaus Leifer | Zendy; A. Cavaleiro | Zendy; Tomáš Polcar | Zendy; M. I. Vasilevskiy | Zendy; F. Vaz | Zendy

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Broadband Optical Absorption Caused by the Plasmonic Response of Coalesced Au Nanoparticles Embedded in a TiO₂ Matrix

Author(s) -

Joel Borges,

Rui M. S. Pereira,

Marco S. Rodrigues,

Tomáš Kubart,

S. Suresh Kumar,

Klaus Leifer,

A. Cavaleiro,

Tomáš Polcar,

M. I. Vasilevskiy,

F. Vaz

Publication year - 2016

Publication title -

the journal of physical chemistry c

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 1.401

H-Index - 289

eISSN - 1932-7455

pISSN - 1932-7447

DOI - 10.1021/acs.jpcc.6b03684

Subject(s) - materials science , plasmon , surface plasmon resonance , nanoparticle , dielectric , molecular physics , annealing (glass) , absorption band , raman spectroscopy , discrete dipole approximation , resonance (particle physics) , optoelectronics , optics , nanotechnology , scattering , chemistry , atomic physics , physics , composite material

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, were experimentally and theoretically studied. The results of the analysis of the Au NPs’ size distributions allowed to conclude that isolated NPs grow only up to 5-6 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, which 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 resonant matching, to electronic transitions in detected species.This research was sponsored by FEDER funds through the COMPETE program (Programa Operacional Factores de Competitividade) and by FCT (Fundação para a Ciência e a Tecnologia), under the projects PEST-C/FIS/UI607/2013, UID/EMS/00285/2013 and PEst-OE/MAT/UI0013/2014. The authors also acknowledge the financial support by the project ESF Research Networking Programme PLASMONBIONANOSENSE. J. Borges also acknowledges the support by the European social fund within the framework of realizing the project “Support of inter sectoral mobility and quality enhancement of research teams at Czech Technical University in Prague”, CZ.1.07/2.3.00/30.0034

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