Plasmonic spheroidal metal nanoshells showing larger tunability and stronger near fields than their spherical counterparts: An effect of enhanced plasmon coupling

Nasrin Hooshmand, Prashant Jain, Mostafa A. El-Sayed

Research output: Contribution to journalArticle

Abstract

Two of the most tunable nanostructure geometries for nanoplasmonics include the metal nanoshell structure and the spheroidal geometry. We systematically investigate the effect of combining both geometries within the same nanostructure. Localized surface plasmon resonances (LSPRs) of spheroidal gold nanoshells are simulated as a function of their aspect ratio. The long-axis LSPR mode of a spheroidal nanoshell red shifts with decreasing shell thickness, similar to a spherical nanoshell. A higher aspect ratio spheroidal nanoshell shows a larger fractional LSPR red shift for the same thickness normalized by core dimensions. This is because coupling between the inner and outer surface plasmons of the nanoshell is stronger for the elongated spheroidal geometry as compared to that for the spherical case, increasing in strength with increasing aspect ratio. It is the result of this enhanced plasmon coupling that spheroidal nanoshells of aspect ratio 4 are over two times more tunable than spherical nanoshells. Also, the plasmonic field enhancement is an order of magnitude larger for the spheroidal nanoshells of aspect ratio 4 as compared to spherical nanoshells. These effects observed in the spheroidal nanoshell are analogous to those in a dimer of spheroidal nanopaticles.

Original languageEnglish (US)
Pages (from-to)374-378
Number of pages5
JournalJournal of Physical Chemistry Letters
Volume2
Issue number5
DOIs
StatePublished - Mar 3 2011
Externally publishedYes

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Nanoshells
aspect ratio
near fields
Metals
surface plasmon resonance
geometry
red shift
metals
Aspect ratio
Surface plasmon resonance
high aspect ratio
plasmons
Geometry
dimers
gold
Nanostructures
augmentation
Plasmons
Gold
Dimers

ASJC Scopus subject areas

  • Materials Science(all)

Cite this

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title = "Plasmonic spheroidal metal nanoshells showing larger tunability and stronger near fields than their spherical counterparts: An effect of enhanced plasmon coupling",
abstract = "Two of the most tunable nanostructure geometries for nanoplasmonics include the metal nanoshell structure and the spheroidal geometry. We systematically investigate the effect of combining both geometries within the same nanostructure. Localized surface plasmon resonances (LSPRs) of spheroidal gold nanoshells are simulated as a function of their aspect ratio. The long-axis LSPR mode of a spheroidal nanoshell red shifts with decreasing shell thickness, similar to a spherical nanoshell. A higher aspect ratio spheroidal nanoshell shows a larger fractional LSPR red shift for the same thickness normalized by core dimensions. This is because coupling between the inner and outer surface plasmons of the nanoshell is stronger for the elongated spheroidal geometry as compared to that for the spherical case, increasing in strength with increasing aspect ratio. It is the result of this enhanced plasmon coupling that spheroidal nanoshells of aspect ratio 4 are over two times more tunable than spherical nanoshells. Also, the plasmonic field enhancement is an order of magnitude larger for the spheroidal nanoshells of aspect ratio 4 as compared to spherical nanoshells. These effects observed in the spheroidal nanoshell are analogous to those in a dimer of spheroidal nanopaticles.",
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